New member rear differential width question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**4X4GMC1972** · 04-05-2005, 05:25 PM

I recently purchased a 1972 GMC 3/4 ton 4x4. I don't believe the rear differential is original to the truck. It is a Dana 60 that I suspect came out of a Ford although it has Delco-Moraine drum brake assemblies. Where the wheels face up to the drums it measures 65" . I believe that I had read in a previous thread that the width should be 66-3/4" for my truck. Is this correct measuring across the drum flanges? If so I will probably install longer studs and make 7/8" spacers for each side to make it the proper track width. Responses will be appreciated.

Blazer1970 · 04-05-2005, 05:39 PM

I believe that 65" is correct for the rear axle in your truck. The front should be about 67".

**4X4GMC1972** · 04-05-2005, 06:35 PM

Tim
I hope you are correct. I do know that the spring perches and shock mounts were relocated to fit my truck. At least it appears that way.
Does anybody know where to find published information regarding the width?
Thanks
Todd

1969 GMC · 04-05-2005, 08:59 PM

My '69 GMC is 67" for the closed knuckle d44 front, and around 65" for the dana 60 rear.

why do you think the D60 is from a Ford? They came under quite a few 3/4 ton GMC's in the 72 and older vintage, and also under some Chevies (and IH's, Dodges, Fords, and possible Studebaker trucks). If you were really worried you can locate a BOM number stamped into one of the axle tubes that will tell you exactly what the axle came from.

also, GM made all their 4x4's with the rear axle slightly narrower, and I wouldn't worry about it if I were you.

**4X4GMC1972** · 04-05-2005, 10:03 PM

Thanks for the replies. I assumed it might have been from a Ford because they were mostly Dana rears from the factory and that the spring perches and shock mounts have been relocated. I am not really worried about it as long it is the proper width. Actually I am very happy with it because the limited slip works perfect.
BTW '69 I like the cab lights. Mine has them too!

Hoods69BadBowTie · 04-06-2005, 01:14 AM

Yeah, I agree I think it should be about 65" across. And yeah Chevy was using this axle then so it should be the right one.
-Later

**JIMs70GMC** · 04-06-2005, 09:17 PM

Yep a lot of GMC used the dana60, mine has one and you can't beat the power-loc rear diff. Also i have a dana60 in my garage that came out of a 71 C20, it's wms-wms is also 65", the perches are in the wrong place though, 42" v. 40" for the 4wd.

04-05-2005, 05:25 PM	#1
4X4GMC1972 Registered User Join Date: Apr 2005 Location: Dallas, Texas Posts: 506	New member rear differential width question I recently purchased a 1972 GMC 3/4 ton 4x4. I don't believe the rear differential is original to the truck. It is a Dana 60 that I suspect came out of a Ford although it has Delco-Moraine drum brake assemblies. Where the wheels face up to the drums it measures 65" . I believe that I had read in a previous thread that the width should be 66-3/4" for my truck. Is this correct measuring across the drum flanges? If so I will probably install longer studs and make 7/8" spacers for each side to make it the proper track width. Responses will be appreciated. __________________ 1978 Dodge Omni

04-05-2005, 05:39 PM	#2
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,507	I believe that 65" is correct for the rear axle in your truck. The front should be about 67". __________________ Tim

04-05-2005, 06:35 PM	#3
4X4GMC1972 Registered User Join Date: Apr 2005 Location: Dallas, Texas Posts: 506	Tim I hope you are correct. I do know that the spring perches and shock mounts were relocated to fit my truck. At least it appears that way. Does anybody know where to find published information regarding the width? Thanks Todd __________________ 1978 Dodge Omni

04-05-2005, 08:59 PM	#4
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	My '69 GMC is 67" for the closed knuckle d44 front, and around 65" for the dana 60 rear. why do you think the D60 is from a Ford? They came under quite a few 3/4 ton GMC's in the 72 and older vintage, and also under some Chevies (and IH's, Dodges, Fords, and possible Studebaker trucks). If you were really worried you can locate a BOM number stamped into one of the axle tubes that will tell you exactly what the axle came from. also, GM made all their 4x4's with the rear axle slightly narrower, and I wouldn't worry about it if I were you. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650 Last edited by 1969 GMC; 04-05-2005 at 09:05 PM.

04-05-2005, 10:03 PM	#5
4X4GMC1972 Registered User Join Date: Apr 2005 Location: Dallas, Texas Posts: 506	Thanks for the replies. I assumed it might have been from a Ford because they were mostly Dana rears from the factory and that the spring perches and shock mounts have been relocated. I am not really worried about it as long it is the proper width. Actually I am very happy with it because the limited slip works perfect. BTW '69 I like the cab lights. Mine has them too! __________________ 1978 Dodge Omni

04-06-2005, 01:14 AM	#6
Hoods69BadBowTie Chevys Kick A$$ Join Date: Jan 2005 Location: Zootown, MT Posts: 12,699	Yeah, I agree I think it should be about 65" across. And yeah Chevy was using this axle then so it should be the right one. -Later __________________ HOODS is what I answer too -'79, '77, '88 Pickup Sold, '85 Camaro, '83 T/A, '81,'83,'90 K5 Blazer All Sold -'79 3/4 ton "Big Yellow Bananna" Lifted 4spd. 39.5 TSL Swampers, The money Pit -'86 K5 Blazer Silverado 6.2 4" lift 35"s -'95 Ext. Cab Shorty 4" Tuff Country rolling 35" M/T's -'83 Monte Carlo T-Tops. 126,500 Original Miles -LATER I would rather push a Chevy then drive a ford!!

04-06-2005, 09:17 PM	#7
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	Yep a lot of GMC used the dana60, mine has one and you can't beat the power-loc rear diff. Also i have a dana60 in my garage that came out of a 71 C20, it's wms-wms is also 65", the perches are in the wrong place though, 42" v. 40" for the 4wd. __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm Last edited by JIMs70GMC; 04-06-2005 at 09:22 PM.

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