Help me ID my rear

[56james]

Is this a GM 10 Bolt? Any help would be great!! Its on a 1956 3100.[IMG][/IMG]

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[joedoh]

removable carrier, no squared off casting below the cover, 10 bolts

edit: I am wrong. Eaton HO33. not a 10 bolt.

[56james]

Thank you the removable carrier was what was throwing me off.

[1project2many]

56james, that is an original type axle. It is not generally called a "ten bolt." There are stamped and cast codes that can be used to determine the age of the axle. Here is the 1955 truck manual section for the rear diff:
http://chevy.oldcarmanualproject.com...55ctsm0401.htm

joedoh, the 8.2 ten bolt came out around 64-65. The terms "ten bolt" and "twelve bolt" were coined to identify whether an axle was a stock "low performance" part or an optional hi-po diff. The 8.2" ring and pinion must be removed from the back of the housing, just like the later 8.5" rear. An original 8.2" cover will usually interchange with the 8.5" cover. Most can be quickly identified by the oil channels stamped into it.




FWIW, this only applies to Chevrolet designed axles. B,O,P, and Caddy did some very different stuff, like putting 12 bolt rear covers on 8.3" axles, using cone style posis, and building a heavy duty 9 3/8" ring gear axle.

Here's a page that can help id some of the GM axles:
http://www.crankshaftcoalition.com/w...identification

And here's a good article on the history of 10 and 12 bolt axles:
http://www.chevydiy.com/history-and-...differentials/

[joedoh]

yes, the earliest 8.2 had a removable carrier without the cast center

[56james]

So I take it most replace this axle with a updated one? Or can these be beefed up to handle an updated power plant like a 5.3L.

[1project2many]

Most people replace them. There's only one easy to find gear ratio and posi centers are as rare as hen's teeth so you can't do much with them.

[joedoh]

for what you would spend on a ring and pinion and a locking unit and then to have it freshened and installed.... you could buy a used gently 10 or 12 bolt posi with the right gears AND buy everyone on this forum a beer.

[Coupeguy2001]

Just saying, they are a stout piece, and seem to run about 225,000 miles before they self destruct.

Nobody uses them anymore because of parts scarcity . There are only 3 ratios available:
3.38, 3,90, and 4.11
the 3.38 ring and pinion will cost you $500, then another 250 to rebuild if all the existing parts are good.
If it needs spider gears, there are a few new sets still available, but add over $200 to the rebuild.

[yossarian19]

Replace the gear oil & run it.
It's called a 55T rear axle. It has a 9 3/8" ring gear. You won't blow it up with a 5.3. If you want to kill this thing, you'll need fire.
Parts are scarce but they can be rebuilt. You can't get a posi or a range of gear ratios, though - so if that's a deal breaker, walk away from it now.