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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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| | | | Joined: Oct 2014 Posts: 4 New Guy | | New Guy Joined: Oct 2014 Posts: 4 | The ring and pinion in my 1970 C60 has way too much backlash.(getting worn out) It is a two speed rear with unknown ratio. The carrier has GM right on top of the third. It is an air braked truck. I have no idea if parts can be found for this axle or not. All along I thought it was an Eaton axle. Did GM make their own rear axles in this era?
Please help me figure out what I'm dealing with. The numbers cast into the housing are 387355 and maybe a 1 after that. (not sure on the 1) | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | There might be numbers stamped into the right side, aft side of axle tube that has additional info.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: Nov 2005 Posts: 6,100 'Bolter | | 'Bolter Joined: Nov 2005 Posts: 6,100 | Hy rockdog, welcome, could you take a couple of pictures and post them here? | | | | | Joined: Feb 2004 Posts: 29,792 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,792 | Is it a vacuum shifted unit, or electric? GM has used both types at different times, and there is a GM corporate axle, and others from different manufacturers. A link to some pictures will be helpful to ID your unit.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Mar 2004 Posts: 6,214 'Bolter | | 'Bolter Joined: Mar 2004 Posts: 6,214 | What engine/trans do you have? Different rears were available with different engine/trans packages. What's the trucks GVW rating? Is there a tag inside the glove box door listing the rear size? Mike B  | | | | | Joined: Oct 2014 Posts: 4 New Guy | | New Guy Joined: Oct 2014 Posts: 4 | Ok I took some pictures. And I'll try to answer the questions. Nothing on the jockey box door for the rear end. Tag on the drivers door says. Rear end 19,000 to 23,000? Gvw on the truck is 32,000. Two speed is electric shift and shift box says eaton on it? But as you can see in the pics. The third has GM cast in the top of the housing. That's what confuses me. Dang can't figure out how to post pics. | | | | | Joined: Feb 2007 Posts: 112 'Bolter | | 'Bolter Joined: Feb 2007 Posts: 112 | You have to post up a Link to your pic's.
Picture's in post's here is not allowed.
Tom | | | | | Joined: Mar 2004 Posts: 6,214 'Bolter | | 'Bolter Joined: Mar 2004 Posts: 6,214 | Looks like the 1970 C60 Air Brake units were only available with the 427 engine. They had a 6.71/9.14 ratio, 23,000 pound rear with 15x7 rear brakes and either a 9,000 or 11,000 pound front axle. Mike B | | | | | Joined: Oct 2014 Posts: 4 New Guy | | New Guy Joined: Oct 2014 Posts: 4 | [quote=Mike B]Looks like the 1970 C60 Air Brake units were only available with the 427 engine. They had a 6.71/9.14 ratio, 23,000 pound rear with 15x7 rear brakes and either a 9,000 or 11,000 pound front axle.
Mike B :)[/quote]
Well they made one with a 366. Because I bought it from a small city and the guy who is their crew manager said his dad ordered it new in 70. And that it was all original. :) | | | | | Joined: Mar 2004 Posts: 6,214 'Bolter | | 'Bolter Joined: Mar 2004 Posts: 6,214 | Looks like the 1970 C60 Air Brake units were only available with the 427 engine. They had a 6.71/9.14 ratio, 23,000 pound rear with 15x7 rear brakes and either a 9,000 or 11,000 pound front axle. Mike B What I should have said was IF you ordered the 23,000 pound 2-speed rear it automatically came with the 427 engine and Air Brakes with the ratios listed above. The 366 with a single speed 17,000 pound rear was the standard issue at 24,000 pound GVW. The 366 could have the optional 17,000 or 18,500 pound 2-speed rears with either Vacuum Over Hydraulic or Full Air brakes. The 17,000 pound axles are Chevrolet/GM and the 18,500 pound are Eaton. Sorry for the confusion, Mike B | | |
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