42.5" !! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

*Fast68Chevy* · 03-28-2002, 03:31 PM

cool ! i just got under the 79 C20 with 14 bolt FF and under the 82 K10 with 10 bolt rea,r and both are 42,5" center to center on leaf packs, which is same as 67-72 2wd 1/2 and 3/4 ton ! we need to keep this info somewhere ! need someone to measure up a 73-87 C10 now, and also blazers. oh wait i have a 78 rear axle i can measure that on

cool stuff!

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Randy- Lincoln, IL
randy@ccaonline.com
-71/C-10(thx teeitup and crews!)350 4+4/CH465(thx 71Chev, GMCPaul, and CPNE)longfleet bed(thnx meathead95)!still building it-
-'84 Z28 H.O. 305 L69 700R4 GT4 3.73
- 1984 Firebird SE 2.8L T-5 GT4 3.73
-1981 Cutlass Supreme, dunno what im gonna do with it yet...
-79 G20 pass van, 350/th350/10bolt
*Paint is overrated
© RSS Enterprises 2000

67Blacksheep · 03-28-2002, 09:12 PM

Fast-
Does this mean that all we would need to do is weld on mounts to accept the coils instead of the leaf springs? I wonder if all the other junk would connect right up? I thought about looking at the panhard on a more modern truck to see if it mounted the same as the one I need. But I don't know if leaf sprung vehicles even have a pan hard set up, do they? If I run across the year you need measured I'll check it out for ya.

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67 Chevy C20 LB Stepside,
350 4-bolt with goodies.

REPO1 · 03-28-2002, 09:22 PM

Do you know what the center-to-center on a '70 C-20 with leafs is?

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Sylvan Lake, Alberta, Canada

1970 Chevy C20 Custom Camper
#s matching 402BB Turbo 400 trans.
Air conditioning, power steering, manual brakes.
73,600 Original Miles!!

REPO1 · 03-28-2002, 09:25 PM

Oh wait, I re-read your post. So the diff in my truck should be 42.5" center-to-center? Does that mean that a 12 bolt from a late '70s to '87 truck should bolt in?

Now you should measure drum to drum on these trucks!!

Thanks for the info....its muchly needed!

Reid

*Fast68Chevy* · 03-28-2002, 10:04 PM

67blacksheep, these measurement are for leaf trucks only, and only 64-72 trucks used coil sprinf panhrd bar type suspension, not 73-up

drum to drum measurement is less than 1.5" difference from 72 to 73 on all axles, they are nothing much different at all, same chassis for the most part besides frame rail channels width and wheelbase, but have different body and body mount frame brackets is all.
i just measured c to c on the 78 Big 10 12 bolt axle and its also 42.5", so ... good deal... only tihng would have to do is relocate shock mounts on all these 73-up axles to put them under a 67-72, would have to use 73-up U bolt upper plates the ones iwth the four holes that sit directly on top of the spring packs which are a better design anyways.

42.5" is what is on the 1/2 and 3/4 ton 2wd 67-82 -or even later maybe- trucks,
and also same on K-10 73-up and C20 73-up, but i cant say for sure on the K20 trucks 73-up.

[This message has been edited by Fast68Chevy (edited March 29, 2002).]

*Fast68Chevy* · 03-29-2002, 01:04 AM

anyone have any comments or info to add to this maybe ? for some reason I always had thought- maybe cuz i had seen other places with ppl who said that 73-up axles spacing was not same- that the 73-up were just a hair off on pad spacing compared to ours, but they actually arent. hmm.... i think i had measure up the 78 axle before but that was before i had ever come across a leaf rear 67-72 10 or 20 truck to measure...

Andy4639 · 03-29-2002, 03:15 AM

Leaf spring rear ends don't have the pan hard bar, because they can't move around like a coil spring rear end can. Hope this helps. I had a junk yard tell me once that a leaf spring rear in a 67 thru 72 are the same as 73 and ups. Have never measured them though.

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Andy
71's Are for ever!!! or 67,68,69,70,72 http://geocities.com/chevy71tpi/main.html

Maximum Overdrive · 03-29-2002, 10:45 AM

Not sure if I got what you wrote correct but are you saying that the leaf pad mounts are the same in the 67-72 as the 73 and up?

*Fast68Chevy* · 03-29-2002, 11:49 AM

Andy, I am not talking about coil spring axle,s at all

what I have been saying, or trying to say, is that 67-72leaf axles have the same spring pad spacing as on the 73-up axles whicch are all leaf

i have not been talking about coil spring 67-72 axles

the only problem is that the pads arent the same in design, but that can be fixed by using 73-up top plates and U bolts if swapping to a 73-up axle. then you have to relocate the shock brackets

[This message has been edited by Fast68Chevy (edited March 29, 2002).]

69 longhorn · 03-29-2002, 12:00 PM

Fast 68,I have a 79 K 20 with the same spacing(42.5).....69 longhorn.

Maximum Overdrive · 03-29-2002, 01:08 PM

Fast thats what I thought you said but I wasnt sure. On my 70 gmc 3/4 2 wd the spacing on rear axle c to c is 41.5, on a 67 4x4 it is 40.5, on my 69 4x4 Im not sure the distance but when I put 73-87 axles on it I had to move the spring pads about a inch to get them to line straight up an down and not at a angle.

69 longhorn · 03-29-2002, 04:49 PM

Overdrive,the 1 tons.....including the longhorns are 40" C to C. It is my understanding that the 4 X 4s share the same spacing. I havent been into the older 4 X4s,so cant sat for sure.....69 longhorn.

Maximum Overdrive · 03-29-2002, 05:28 PM

Could be. I'm not sure what axle or ratio is in the 3/4 Gmc as I can find no numbers anywhere on it to identify it.

trukman1 · 03-30-2002, 11:17 PM

Well guys, the spacing on my '69 K10 was 40" and the spacing on the 14FF from my '77 was 42.5" so I had to move the spring pads in and remount the shock mounts. Go Figure!

Mitzki5 · 03-31-2002, 12:16 AM

I have a 69 GMC with leaf springs and 12 bolt rear. I will measure in the morning. I hope that 73 and up will fit. That would be great! I'll post what I find.

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Mitzki5
69 GMC Shortbed
Central, Illinois

Scrub · 03-31-2002, 01:07 AM

A newer axle will bolt right up to a 2wd. A 4x4 is narrower and you will have to reweld the spring pads.

03-28-2002, 03:31 PM	#1
Fast68Chevy Account Suspended Join Date: May 2000 Location: IL Posts: 0	42.5" !! cool ! i just got under the 79 C20 with 14 bolt FF and under the 82 K10 with 10 bolt rea,r and both are 42,5" center to center on leaf packs, which is same as 67-72 2wd 1/2 and 3/4 ton ! we need to keep this info somewhere ! need someone to measure up a 73-87 C10 now, and also blazers. oh wait i have a 78 rear axle i can measure that on cool stuff! ------------------ Randy- Lincoln, IL randy@ccaonline.com -71/C-10(thx teeitup and crews!)350 4+4/CH465(thx 71Chev, GMCPaul, and CPNE)longfleet bed(thnx meathead95)!still building it- -'84 Z28 H.O. 305 L69 700R4 GT4 3.73 - 1984 Firebird SE 2.8L T-5 GT4 3.73 -1981 Cutlass Supreme, dunno what im gonna do with it yet... -79 G20 pass van, 350/th350/10bolt *Paint is overrated © RSS Enterprises 2000

03-28-2002, 09:12 PM	#2
67Blacksheep Registered User Join Date: Mar 2002 Location: Ohio Posts: 135	Fast- Does this mean that all we would need to do is weld on mounts to accept the coils instead of the leaf springs? I wonder if all the other junk would connect right up? I thought about looking at the panhard on a more modern truck to see if it mounted the same as the one I need. But I don't know if leaf sprung vehicles even have a pan hard set up, do they? If I run across the year you need measured I'll check it out for ya. ------------------ 67 Chevy C20 LB Stepside, 350 4-bolt with goodies. __________________ '94 GMC Seirra Ext. Cab '67 Formula Firebird '89 GSX-R 750

03-28-2002, 09:22 PM	#3
REPO1 Shortbox wanna-be. Join Date: Mar 2002 Location: Fort St.John, British Columbia, Canada Posts: 773	Do you know what the center-to-center on a '70 C-20 with leafs is? ------------------ Sylvan Lake, Alberta, Canada 1970 Chevy C20 Custom Camper #s matching 402BB Turbo 400 trans. Air conditioning, power steering, manual brakes. 73,600 Original Miles!! __________________ 1970 Chevy C20 Custom Camper 402BB Turbo 400 trans. (Slowly becoming a '70 shortbox 1/2 ton) '71 Camaro SS 402/T400 resto '97 Z28 (11.41@127MPH)

03-28-2002, 09:25 PM	#4
REPO1 Shortbox wanna-be. Join Date: Mar 2002 Location: Fort St.John, British Columbia, Canada Posts: 773	Oh wait, I re-read your post. So the diff in my truck should be 42.5" center-to-center? Does that mean that a 12 bolt from a late '70s to '87 truck should bolt in? Now you should measure drum to drum on these trucks!! Thanks for the info....its muchly needed! Reid __________________ 1970 Chevy C20 Custom Camper 402BB Turbo 400 trans. (Slowly becoming a '70 shortbox 1/2 ton) '71 Camaro SS 402/T400 resto '97 Z28 (11.41@127MPH)

03-29-2002, 03:15 AM	#7
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Leaf spring rear ends don't have the pan hard bar, because they can't move around like a coil spring rear end can. Hope this helps. I had a junk yard tell me once that a leaf spring rear in a 67 thru 72 are the same as 73 and ups. Have never measured them though. ------------------ Andy 71's Are for ever!!! or 67,68,69,70,72 http://geocities.com/chevy71tpi/main.html __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

03-28-2002, 10:04 PM	#5
Fast68Chevy Account Suspended Join Date: May 2000 Location: IL Posts: 0	67blacksheep, these measurement are for leaf trucks only, and only 64-72 trucks used coil sprinf panhrd bar type suspension, not 73-up drum to drum measurement is less than 1.5" difference from 72 to 73 on all axles, they are nothing much different at all, same chassis for the most part besides frame rail channels width and wheelbase, but have different body and body mount frame brackets is all. i just measured c to c on the 78 Big 10 12 bolt axle and its also 42.5", so ... good deal... only tihng would have to do is relocate shock mounts on all these 73-up axles to put them under a 67-72, would have to use 73-up U bolt upper plates the ones iwth the four holes that sit directly on top of the spring packs which are a better design anyways. 42.5" is what is on the 1/2 and 3/4 ton 2wd 67-82 -or even later maybe- trucks, and also same on K-10 73-up and C20 73-up, but i cant say for sure on the K20 trucks 73-up. [This message has been edited by Fast68Chevy (edited March 29, 2002).]

03-29-2002, 01:04 AM	#6
Fast68Chevy Account Suspended Join Date: May 2000 Location: IL Posts: 0	anyone have any comments or info to add to this maybe ? for some reason I always had thought- maybe cuz i had seen other places with ppl who said that 73-up axles spacing was not same- that the 73-up were just a hair off on pad spacing compared to ours, but they actually arent. hmm.... i think i had measure up the 78 axle before but that was before i had ever come across a leaf rear 67-72 10 or 20 truck to measure...

03-29-2002, 10:45 AM	#8
Maximum Overdrive December 21, 2012 Join Date: Apr 2000 Location: Black Eagle, Montana Posts: 1,634	Not sure if I got what you wrote correct but are you saying that the leaf pad mounts are the same in the 67-72 as the 73 and up? __________________ *"!Ama Sua, Ama Kjella, Ama Lllulla!"*

03-29-2002, 11:49 AM	#9
Fast68Chevy Account Suspended Join Date: May 2000 Location: IL Posts: 0	Andy, I am not talking about coil spring axle,s at all what I have been saying, or trying to say, is that 67-72leaf axles have the same spring pad spacing as on the 73-up axles whicch are all leaf i have not been talking about coil spring 67-72 axles the only problem is that the pads arent the same in design, but that can be fixed by using 73-up top plates and U bolts if swapping to a 73-up axle. then you have to relocate the shock brackets [This message has been edited by Fast68Chevy (edited March 29, 2002).]

03-29-2002, 12:00 PM	#10
69 longhorn Registered User Join Date: Aug 2001 Location: rock island,il,usa Posts: 5,382	Fast 68,I have a 79 K 20 with the same spacing(42.5).....69 longhorn. __________________ http://community.webshots.com/user/hotrodhorn

03-29-2002, 01:08 PM	#11
Maximum Overdrive December 21, 2012 Join Date: Apr 2000 Location: Black Eagle, Montana Posts: 1,634	Fast thats what I thought you said but I wasnt sure. On my 70 gmc 3/4 2 wd the spacing on rear axle c to c is 41.5, on a 67 4x4 it is 40.5, on my 69 4x4 Im not sure the distance but when I put 73-87 axles on it I had to move the spring pads about a inch to get them to line straight up an down and not at a angle. __________________ *"!Ama Sua, Ama Kjella, Ama Lllulla!"*

03-29-2002, 04:49 PM	#12
69 longhorn Registered User Join Date: Aug 2001 Location: rock island,il,usa Posts: 5,382	Overdrive,the 1 tons.....including the longhorns are 40" C to C. It is my understanding that the 4 X 4s share the same spacing. I havent been into the older 4 X4s,so cant sat for sure.....69 longhorn. __________________ http://community.webshots.com/user/hotrodhorn

03-29-2002, 05:28 PM	#13
Maximum Overdrive December 21, 2012 Join Date: Apr 2000 Location: Black Eagle, Montana Posts: 1,634	Could be. I'm not sure what axle or ratio is in the 3/4 Gmc as I can find no numbers anywhere on it to identify it. __________________ *"!Ama Sua, Ama Kjella, Ama Lllulla!"*

03-30-2002, 11:17 PM	#14
trukman1 Registered User Join Date: Apr 2001 Location: Beavercreek, Ohio 45431 Posts: 737	Well guys, the spacing on my '69 K10 was 40" and the spacing on the 14FF from my '77 was 42.5" so I had to move the spring pads in and remount the shock mounts. Go Figure! __________________ 1967 K30 461/TH400/Np205/D60/14FF/BDS MTZ 375/75/16 on 16x10 Pro Comps

03-31-2002, 12:16 AM	#15
Mitzki5 "TRUCKLESS" Join Date: Jan 2002 Location: Tuscola IL Posts: 457	I have a 69 GMC with leaf springs and 12 bolt rear. I will measure in the morning. I hope that 73 and up will fit. That would be great! I'll post what I find. ------------------ Mitzki5 69 GMC Shortbed Central, Illinois __________________ Mitzki5 No longer have an old truck! But always looking for another one!



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03-31-2002, 01:07 AM	#16
Scrub Collector of rusty Items Join Date: Dec 2001 Location: Sisters,Oregon USA Posts: 731	A newer axle will bolt right up to a 2wd. A 4x4 is narrower and you will have to reweld the spring pads. __________________ Scrub Sisters, Oregon - Home of the Sisters Rodeo. 70 GMC 1,000,000 + miles 72 K-20 project, 456 Dana60 front, Corp14 rear w/locker, 265R19.5 tires 20-ply. Warn 12k winches both ends, Cross-over steering with raised tie-rod, Powerbox steering, 4500 watt 120-AC power, Air, Hydraulic aux power, 4 inch lift, 5000 lb air-bags both ends.

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