Leaf spring perch variations??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

HSRACER · 09-28-2015, 11:32 PM

I have removed two rear differentials out of leaf spring 1970 2wd trucks. One 6 lug chevy and an 8 lug gmc. Both the perches on these diffs measure 42.5 inches center to center.

I have had a couple of people interested in purchasing these for different trucks. One had a 1965 chevy 4x4 and his perches measured 40.25 inches center to center so they wouldn't fit.

Another guy measured his 1971 4x4 blazer perches and they were also 40.25 inches center to center.

My question is were all 4x4 differentials set at the 40.25 inch setting and 2wd diffs set at 42.5 for our 67-72 trucks?

I could use an education!!! Thank in advance for your insight.

HSRACER · 09-29-2015, 04:55 PM

I can't believe there have been no comments or information on this thread. Is it to boring to get any input on?????

**71blksuper4x4** · 09-29-2015, 08:44 PM

Yes, 2wd is 42.5" center to center and c30/cab & chassis/4x4 are 40" center.

**71blksuper4x4** · 09-29-2015, 08:47 PM

73+ axles:
2wd and K10-K20 are 42.5 centers
C30/K30/c&c are 40" centers

Mike C · 09-29-2015, 09:46 PM

I concur with the above. 40.5" on 67-72 4x4 and 42.5" on
73 and up 1/2 and 3/4 ton with the K30 at 40.5".

The '69-'72 4x4 trucks also use 2 1/2" wide leaf springs and the 2x4 use 2" wide springs. Longhorn trucks are 2 wheel drive but they have 40.5" spring centers and use 2 1/2" springs just to mix things up.

Not a '67-'68 guy so can't speak to what they had but I know the springs are different.

HSRACER · 09-30-2015, 10:10 AM

Quote:

Originally Posted by Mike C

I concur with the above. 40.5" on 67-72 4x4 and 42.5" on
73 and up 1/2 and 3/4 ton with the K30 at 40.5".

The '69-'72 4x4 trucks also use 2 1/2" wide leaf springs and the 2x4 use 2" wide springs. Longhorn trucks are 2 wheel drive but they have 40.5" spring centers and use 2 1/2" springs just to mix things up.

Not a '67-'68 guy so can't speak to what they had but I know the springs are different.

Weren't the 73+ axles also wider than the 72 and down?

Mike C · 09-30-2015, 03:52 PM

I don't think so. 4 Wheel Parts shows replacement axle the same for '70-'81 8 7/8" axle.

09-28-2015, 11:32 PM	#1
HSRACER Registered User Join Date: Sep 2007 Location: Katy TX Posts: 1,268	Leaf spring perch variations??? I have removed two rear differentials out of leaf spring 1970 2wd trucks. One 6 lug chevy and an 8 lug gmc. Both the perches on these diffs measure 42.5 inches center to center. I have had a couple of people interested in purchasing these for different trucks. One had a 1965 chevy 4x4 and his perches measured 40.25 inches center to center so they wouldn't fit. Another guy measured his 1971 4x4 blazer perches and they were also 40.25 inches center to center. My question is were all 4x4 differentials set at the 40.25 inch setting and 2wd diffs set at 42.5 for our 67-72 trucks? I could use an education!!! Thank in advance for your insight. __________________ HSRACER Slammed 53 5 window Blown/Bagged 54 Pickup Patinaed 67 LS stepside Supercharged 67 Nova Bagged 69 Suburban Turbo'ed 5.3 LS Last edited by HSRACER; 09-28-2015 at 11:53 PM.

09-29-2015, 04:55 PM	#2
HSRACER Registered User Join Date: Sep 2007 Location: Katy TX Posts: 1,268	Re: Leaf spring perch variations??? I can't believe there have been no comments or information on this thread. Is it to boring to get any input on????? __________________ HSRACER Slammed 53 5 window Blown/Bagged 54 Pickup Patinaed 67 LS stepside Supercharged 67 Nova Bagged 69 Suburban Turbo'ed 5.3 LS

09-29-2015, 08:44 PM	#3
71blksuper4x4 SWB 4x4 Collector Join Date: Jun 2001 Location: Osage City, KS Posts: 5,149	Re: Leaf spring perch variations??? Yes, 2wd is 42.5" center to center and c30/cab & chassis/4x4 are 40" center. __________________ TREVOR 1970 CST swb 4x4 (speedwarning,cruise,tilt,tach,8track, original red shoulder belts,tow hooks) 1972 Jimmy (soon to be Hickey cloned) 1971 Cheyenne Super 4x4 swb (tilt,tach,buckets, original blue shoulder belts,am/fm,cruise,tow hooks, dealer 8 track) 1972 Cheyenne Super K20 4x4 Custom Camper (tilt, tach, am/fm, tow hooks, bed toolbox, aux gas tank 1972 Cheyenne Super Crew Cab K30 4x4 Duramax, Allison, np205, buckets, tow hooks (CURRENT PROJECT) http://67-72chevytrucks.com/vboard/s...d.php?t=624819 1989 V3500 Crew Cab (454tbi, NV4500, np205) 1970 Chevelle SS (LS5 454,th400,8track,buckets,tach) :2004 Jeep Wrangler Rubicon (daily driver) WTB: 1968-70 Cruise Control Lever

09-29-2015, 08:47 PM	#4
71blksuper4x4 SWB 4x4 Collector Join Date: Jun 2001 Location: Osage City, KS Posts: 5,149	Re: Leaf spring perch variations??? 73+ axles: 2wd and K10-K20 are 42.5 centers C30/K30/c&c are 40" centers __________________ TREVOR 1970 CST swb 4x4 (speedwarning,cruise,tilt,tach,8track, original red shoulder belts,tow hooks) 1972 Jimmy (soon to be Hickey cloned) 1971 Cheyenne Super 4x4 swb (tilt,tach,buckets, original blue shoulder belts,am/fm,cruise,tow hooks, dealer 8 track) 1972 Cheyenne Super K20 4x4 Custom Camper (tilt, tach, am/fm, tow hooks, bed toolbox, aux gas tank 1972 Cheyenne Super Crew Cab K30 4x4 Duramax, Allison, np205, buckets, tow hooks (CURRENT PROJECT) http://67-72chevytrucks.com/vboard/s...d.php?t=624819 1989 V3500 Crew Cab (454tbi, NV4500, np205) 1970 Chevelle SS (LS5 454,th400,8track,buckets,tach) :2004 Jeep Wrangler Rubicon (daily driver) WTB: 1968-70 Cruise Control Lever

09-29-2015, 09:46 PM	#5
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,714	Re: Leaf spring perch variations??? I concur with the above. 40.5" on 67-72 4x4 and 42.5" on 73 and up 1/2 and 3/4 ton with the K30 at 40.5". The '69-'72 4x4 trucks also use 2 1/2" wide leaf springs and the 2x4 use 2" wide springs. Longhorn trucks are 2 wheel drive but they have 40.5" spring centers and use 2 1/2" springs just to mix things up. Not a '67-'68 guy so can't speak to what they had but I know the springs are different. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

09-30-2015, 03:52 PM	#7
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,714	Re: Leaf spring perch variations??? I don't think so. 4 Wheel Parts shows replacement axle the same for '70-'81 8 7/8" axle. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax



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