help with rear end identification

[billo92]

so i bought this 1958 step-side short-box apache. when i took off the rear drums they were filled with diff lube so i knew i was gonna have to replace the axle seals. but when i got the diff apart i found a ton of wear on the carrier pin (which was causing a ton of slop/play in the pinion). so i started trying to figure out what rear end it was so i could hopefully get some new parts for it. well.... its a 10 stud cover, with a drop out third member (also 10 studs) the ring gear is 9.5 inches diameter across the middle (im not even sure if thats the correct way to measure the ring gear, because when i measure straight along the open edge of the carrier it measures 8.5 inches exactly, which is of course a common 10 bolt gm size?) the ratio of the rear end is 3.90:1 (39 on the ring gear 10 on the pinion gear) so i went online to try and find anything out about this rear end and i cant find anything about a 10 bolt 9.5 inch 3.90:1 ratio rear end or anything close to it. this is a problem because i cant find parts until i know what i need. if it helps the ring gear is held to the carrier with 12 bolts and the axles are 17 spline. oh, and the ring gear is stamped "gm" and then a part number and the gear numbers 39-10 and its non posi.

any help as to what rear end this is and/or where i can find replacement parts for it is greatly appreciated. thank you!

bill

[dwcsr]

Not sure on what you mean by carrier pin, and when you say slop in the pinion do you mean up and down or back lash? The rear is a stock GM rear for that year. Parts are hard to find new or NOS, You may need to find another good rear to fix what you have.

You need to look at the axle shaft bearing surfaces, If it was leaking badly then the surfaces are most likely very pitted and you will need axles as well.

[billo92]

by carrier pin i mean the pin that holds the spider gears in the carrier. the pinion seemed to have a lot of backlash (because of the pin holding the spider gears moving), and i did clean off the axles and check, they actually show barely any wear but the seals were pretty brittle and had two cracks in each of them =/ i had a feeling it was a stock rear end but i was wondering what the technical term for it would be? 10 bolt 9.5? 10 bolt 8.5? i found a few places that sold parts for a 10 bolt 8.5 including side gears with 17 splines for the axles so i had a feeling that was correct but i wanted to make sure. thanks for your help

[raycow]

You have the stock 1/2 ton rear which was basically the same from 55 to 62. GM's designation for it was H033. Some aftermarket vendors call it a 55T. Others call it an Eaton, which is incorrect, because it was always made by GM.

It is a very tough, strong rear, and has no real problems apart from limited gearing choices and parts availability. You can still get bearings, seals and gaskets, but not a whole lot else. Fortunately, the spider pin appears to be the same as used in the later 12 bolt rear.
http://www.ringpinion.com/PartsList....fID=37&CatID=9

The 17 spline 8.5" rear you found was used in Chevy cars, and very little from that will interchange with the truck rear.

Btw, if you have problems with excessive shaft end play, the cheap fix is to install a new spacer block wide enough to take up the extra clearance. GM used to sell these in a couple of different sizes, but they haven't been available for quite a long time. It is a very easy job for any machine shop to make one.

Ray

[billo92]

thank you ray! i had actually saved that page in a bookmark but wasnt sure if it was e correct part, but now that i know the 55t or ho 33 name designation and did some research thats definetly right. thanks again!