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?
