What Axle Ratio Do I Have? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

67RS/SSx2 · 09-04-2021, 10:45 PM

Here is my SPID. I have a 1972 C20 with L47 402 CI big block, the G70 rear leaf springs, and M49 turbo hydromatic transmission. On the build sheet under axle it shows "R K H".

Looking at page 9 of the 1972 Chevy truck specification manual from the GM heritage center it shows I should have a Dana 5500 rear (what the heck is that?) and 3.54 axle ratio since no optional axle ratio is shown on the SPID. Do I have this correct? Thanks!

mr.mud1 · 09-05-2021, 12:26 AM

Quote:

Originally Posted by 67RS/SSx2

Here is my SPID. I have a 1972 C20 with L47 402 CI big block, the G70 rear leaf springs, and M49 turbo hydromatic transmission. On the build sheet under axle it shows "R K H".

Looking at page 9 of the 1972 Chevy truck specification manual from the GM heritage center it shows I should have a Dana 5500 rear (what the heck is that?) and 3.54 axle ratio since no optional axle ratio is shown on the SPID. Do I have this correct? Thanks!

hi,my truck is the same,1972 Cheyenne super 20,402,turbo 400 (M49),G70 heavy rear spring and a Dana 60 rear with the code RKH on my build sheet and that is a 3.54 ratio.metal tag on one of my rear cover bolts confirms this.on the lower right side of the rear housing,below the axle tube,an inch or so over from the rear cover,there is "60" in raised letters cast in the web on the housing.take care.Greg

**Already Gone** · 09-05-2021, 12:52 AM

Maybe this will help.

**special-K** · 09-05-2021, 07:20 AM

Yep, Dana 60/3.54:1 ratio. That's how the big block automatics came through.

factorystock · 09-05-2021, 09:18 PM

Back in the day, many heavy camper owners were not happy about the mandatory 3.54 ratio with the big block. For better performance, they were told to ditch the tall 7.50- 16 about 32" diameter and replace them with 8.00-16.5 28.6" to get the rpm's up. Looking back, IMO, was a big shortcoming Chevy didn't offer the 3.73 in C 20's in this era when buyers really needed it for hauling a heavy camper and pulling a boat. Under COPO, a 4.10 could have been special ordered.

Mike C · 09-05-2021, 11:36 PM

Great thing about Dana axles is they put a ratio tag under one of the cover bolts. So if nobody has messed with it that will still be there.

67RS/SSx2 · 09-06-2021, 11:02 PM

I will have to check to see if my axle has a tag on it.

Got my fuel leak fixed today (another thread). Took a trip down route 66 for its maiden voyage to take the wife to dinner. About 30 miles round trip. Absolutely love the way this truck drives.

My speedometer is in near perfect agreement with Google on speed. Whatever axle is in it, it seems to match the transmission speedo gear very well. I suspect it is the 3.54. I need to jack the rear up to see if it has a limited slip rear (not on the SPID but it may have been added). If it does I can do a rough verification of the gearing.

By the way, the wife loves this truck (even with a rough body). She is already talking about ordering a Highlander seat cover from SMS (going to try to call them tomorrow) and a blue spray-in bed liner liner to match the truck. She has even talked about taking MY truck

on some of her shopping trips!

09-04-2021, 10:45 PM	#1
67RS/SSx2 Registered User Join Date: Sep 2010 Location: Central Oklahoma Posts: 253	What Axle Ratio Do I Have? Here is my SPID. I have a 1972 C20 with L47 402 CI big block, the G70 rear leaf springs, and M49 turbo hydromatic transmission. On the build sheet under axle it shows "R K H". Looking at page 9 of the 1972 Chevy truck specification manual from the GM heritage center it shows I should have a Dana 5500 rear (what the heck is that?) and 3.54 axle ratio since no optional axle ratio is shown on the SPID. Do I have this correct? Thanks! Attached Images __________________ 1972 C20 402/TH400/3.54 Highlander 1969 Camaro RS with SS trim, 1967 Camaro RS/SS (sold) 1983 GMC Sierra Classic 2500 crew cab (sold) 1972 Chevy C10 Cheyenne Super (sold) 1984 Chevy Silverado C20 crew cab (bought new by my uncle, in the family until I sold it)

09-05-2021, 12:52 AM	#3
Already Gone 70+ ( Old Skool Club ) Join Date: Nov 2003 Location: Saskatoon, Saskatchewan ,Canada Posts: 9,129	Re: What Axle Ratio Do I Have? Maybe this will help. Attached Images __________________ 1972 C10 Custom/Deluxe 613 Highlander 406/700R4 1999 White Tahoe LS 4x2 with Z56 Police Package 1992 K1500 GMC Suburban Members I have personally met: MusicMan70 - HeavyD - ChewyChevy67 - StingRay -71SWB4x4 - 67 Burb - DeadheadNM - too much stuff - bc65 - das601 " Circumsatances Do Not Change Responsibility " " The Sky is not the Limit, Your Mind is." Marilyn Monroe .. RIP Charlie Watts 1941 - 2021

09-05-2021, 07:20 AM	#4
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,858	Re: What Axle Ratio Do I Have? Yep, Dana 60/3.54:1 ratio. That's how the big block automatics came through. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

09-05-2021, 09:18 PM	#5
factorystock Registered User Join Date: Feb 2007 Location: west coast Posts: 3,376	Re: What Axle Ratio Do I Have? Back in the day, many heavy camper owners were not happy about the mandatory 3.54 ratio with the big block. For better performance, they were told to ditch the tall 7.50- 16 about 32" diameter and replace them with 8.00-16.5 28.6" to get the rpm's up. Looking back, IMO, was a big shortcoming Chevy didn't offer the 3.73 in C 20's in this era when buyers really needed it for hauling a heavy camper and pulling a boat. Under COPO, a 4.10 could have been special ordered.

09-05-2021, 11:36 PM	#6
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,722	Re: What Axle Ratio Do I Have? Great thing about Dana axles is they put a ratio tag under one of the cover bolts. So if nobody has messed with it that will still be there. __________________ 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

09-06-2021, 11:02 PM	#7
67RS/SSx2 Registered User Join Date: Sep 2010 Location: Central Oklahoma Posts: 253	Re: What Axle Ratio Do I Have? I will have to check to see if my axle has a tag on it. Got my fuel leak fixed today (another thread). Took a trip down route 66 for its maiden voyage to take the wife to dinner. About 30 miles round trip. Absolutely love the way this truck drives. My speedometer is in near perfect agreement with Google on speed. Whatever axle is in it, it seems to match the transmission speedo gear very well. I suspect it is the 3.54. I need to jack the rear up to see if it has a limited slip rear (not on the SPID but it may have been added). If it does I can do a rough verification of the gearing. By the way, the wife loves this truck (even with a rough body). She is already talking about ordering a Highlander seat cover from SMS (going to try to call them tomorrow) and a blue spray-in bed liner liner to match the truck. She has even talked about taking MY truck on some of her shopping trips! __________________ 1972 C20 402/TH400/3.54 Highlander 1969 Camaro RS with SS trim, 1967 Camaro RS/SS (sold) 1983 GMC Sierra Classic 2500 crew cab (sold) 1972 Chevy C10 Cheyenne Super (sold) 1984 Chevy Silverado C20 crew cab (bought new by my uncle, in the family until I sold it)



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