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Replacing the companion flange oil seal on the 10 bolt 58 Chevy 1/2 ton rear end and need a new pinion shaft nut. Does anyone have a source for those? Its 1 1/8 OD and a 7/8x16 thread. It may, emphasize may, be GM part 1185837 but I'm not sure about that. Local NAPA says that # does not cross check with anything. I know its a Buick pinion shaft nut from about 1956-60 and think it may be the same as the 10 bolt rear end in my pickup.

A source or an accurate part # would be great because right now things are at full stop in getting it back together.

Thanks for any help.
Jerry

Call a Carquest store & have them look in the Help line of parts. I don,t have the catalog here at home but I think it might be in there. Did you call a G. M. dealer? I believe L.M.C. has it but it would take a few day,s to get there.

seems to me I got one at NAPA some time back when I did my pinion bearing

Bill

Tried both CarQuest and NAPA. CQ had a box of metric spindle nuts for FWD but no SAE and nothing that resembled my companion flange/yoke nut. NAPA here is usually very helpful but they stock only 7/8x14. Chevy dealership was less than helpful also. Tried several auto parts, looked on ebay, craigs list etc. No Luck so far and I can't use the old one as the threads were galled when it was removed or maybe were pulled when it was torqued to 240 ft. lb originally.

Can anyone identify the rear end beyond 10 bolt? It might help if I could give parts people the rear end identification. 58 Chevy half-ton 10 bolt isn't too helpful according to them.

Thanks for the suggestions.
Jerry

Try the aftermarket gear vendors, such as Richmond Gear. They've probably got an assortment of pinion nuts that will interchange.
Jerry

If it is the non-positraction GM corporate axle (the one with the removeable pumpkin)It is GM part number #3736464 (7/8-16) It also fits Chevrolet pass cars 1955-66 and probably beyond
Plus the 1955-62 1/2 ton trucks.

Here are a couple of more GM numbers that interchange

Part Number Cross Reference
3736464
Replaces 3752901
Replaces 3887866

Thank you all very much for the suggestions. I hadn't tried the sources from hotrod lincoln or wdoftexas.

The rear end seems to be 1958 1/2 ton and a 10-bolt--as I counted them on the rear cover. The number on the front pinion bearing cross checks to a bearing for a 58 1/2 ton and the wheel cylinder cast # cross check to 58-59 Chevy 1/2 ton. So I concluded its most likely a 58 1/2 ton rear end.

I will admit my ignorance about the GM corporate axle and wouldn't know it if it was staring at me. On the rear end there are studs on which the rear cover mounts and studs on which the front is mounted and presumably can be removed. If both were removed you would be left with axle housings and a big round '0' in the center. Maybe I ought to do a search on this site for it and educate myself.

This site is a great resource thanks to the members.

Jerry

I,ve got a used one i,ll send you if you want.
What about a standard nut from a heavy equipment dealer with a little thread locker on it.

I am replacing the rear end in my 57 1/2 ton 3200. I believe it is the same rear you have in yours.If I can get the nut off mine without damaging it I can mail it to you if you can't find anything new.3

Thanks for the offers and suggestions. I have found a part number thanks for wdoftexas and the site www.oldsmobility.com/10bolt-tech.htm

The pinion shaft nut is GM part 3736464 and is a
7/8 x16 thread and is 1 1/8 across the flats.

I was also able to confirm the rear end is a 10 bolt first series for 55-64 GM and is a 3.9:1 ratio which I gather is pretty standard for the pickups. So my information that it was from a 58-59 chevy 1/2 ton seems correct as both the wheel cylinder number and front pinion bearing number check out as 58-59 1/2 ton rear end.

Jerry