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#16028 02/03/2004 8:00 AM | Joined: Jan 2004 Posts: 10 Member | | Member Joined: Jan 2004 Posts: 10 | Finally identified the rear axle in my '71 C-20. It's an Eaton, either an HO52 or HO72.
Supposedly the brake shoes are different sizes between the two, the rest of the axle is the same. The HO52 is supposed to be 3/4 ton and the HO72 is a 1 ton. Could also be that the only differenc are the spring perches, being set up for coils on the HO52 and leaf springs on the HO72. Details are sketchy.
Also sketchy is the axle ratio. Supposedly 4.56 is high as they go, but mine appear to be 4.10. One source says this axle never came in 4.10. Will probably have to pull the cover off and count the teeth. The 4.56 and 5.14 are supposed to be the common sizes for GM trucks, both pickup and step vans.
On the plus side this axle is said to be stronger than a Dana 60, approaching a Dana 70.
Bad news is parts are all but impossible to find.
Which brings us to these question:
Anyone know a parts supplier who handles this axle?
Are posi's or lockers available? | | |
#16029 02/03/2004 8:22 AM | Joined: Feb 2001 Posts: 1,897 Member | | Member Joined: Feb 2001 Posts: 1,897 | This used to be the only rear end that came from the factory with a Detroit Locker. There are parts available if you look hard enough..I want to say Art Howsers(sp?)Rear end Service,,,My brain does wander off in odd directions sometimes  
There is enough good in the worst of us and enough bad in the best of us that it does not behoove any of us to criticize the rest of us.
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Be yourself. If you are ever lost, It will be much easier to find yourself if you know who you are!
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#16030 02/04/2004 1:48 AM | Joined: Jul 2003 Posts: 101 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2003 Posts: 101 | I have been told that GM 3/4 and 1 ton with automatic from ~1967 to 1972 had 4.11 gears. 4 speeds had 4.56. In about 1980 I bought a new Detroit Locker for my 1953 3/4 ton with Eaton axle. I bet you can still get them. | | |
#16031 02/04/2004 2:26 AM | Joined: Apr 2002 Posts: 1,571 Shop Shark | | Shop Shark Joined: Apr 2002 Posts: 1,571 | I think that Detroit Locker has been out of production for quite some time now. Also, the 4.11 gears were optional in all the trucks, mine came out of a 4-speed. | | |
#16032 02/05/2004 4:59 AM | Joined: Jan 2004 Posts: 112 'Bolter | | 'Bolter Joined: Jan 2004 Posts: 112 | Brian,
If your going to upgrade your rearend I would like to buy your 4:10 for my 49 3/4. I've got 4:57's now.
If your truck is an automatic then it is almost certainly a 4:10 ratio and some manual trans. also had the 4:10 but most were 4:57. Give me a shout if I can get the pumpkin from you. - Terry
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#16033 02/06/2004 3:24 AM | Joined: Oct 2003 Posts: 54 Member | | Member Joined: Oct 2003 Posts: 54 | My 61 has this axle under it, 3/4 ton, 4 speed, with 4.56. Love the size and strength, but parts are $$$$$. An example: new pinion bearings--$180 for the big one, $40 for the small one. I've actually had pretty good luck at a mom-and-pop parts store here in town thats been around for years. The only problem I have with mine is that the seals leak constantly because there are grooves worn around where the seal rides. Tough to keep the wheels clean. Let me know if you find any other good sources for parts. | | |
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