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Discussion Starter #1 (Edited)
I recently picked up an older chevy rearend that I think is from the 50's-early60's, and have been unable to find any information for it. From the other threads I read, it appears that there is little information on rears. Anyway, the markings are 3725899 J16 GM18 and 3725899 G99 Gm18 (I have two). The chunks remove from the front. The ring carried is marked C-30751 and is stamped ARMA STEEL. Looks like a posi unit with 11 pinion and 37 ring teeth (3.36?) I have a picture but I get a message that the file is to big to download. I will try to get pic loaded. I would appreciate any information that I can get. I'm really shocked to find so much information on the later 10 and 12 bolts but no info on the older units. Happy Holidays and thanks in advance.

Got photos loaded under my gallery : )
 

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Don't know about the numbers, but..............

If it's the pic in your gallery, and that's a drain plug in the bottom of the housing, it's a 57 Chevy rear end.

55-57 had leaf springs and only 57 had the drain plug.

Looks like the posi unit I had in my 55.
 

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Discussion Starter #3
Thanks Poncho62, I figured it was around a late fifties but was unsure. Its interesting that only the 57 had the drain plug on the bottom like that. Any idea if these rears are hard to get or if there are alot of them out there?
 

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RC, I agree with Poncho. The 3rd member will fit into the 55-64 axle housings, but you may have to get some spacer kits to make ever thing fit up correctly. Also, there are "family" groups that must be matched to the rear end ratios such as 3.08 thru 3.56 is one group and 3.78 thru 4.56 is another. The newer the rear end, the better because of the improvements that were made each year in the bearings, seals etc. I am presently using a 64 in my 36 coupe and a 57 in my 36 pickup. The 57 has 64 wheel bearings and seals and an after-market posi gear section. I have three spare 57 3rd members, a 55 and a 64 3rd members so I guess they would be fairly common. Yours may be important to a restoration buff that wants to match up numbers, but other than that, $ 75 is all I will pay for what appears to be a good and serviceable 3rd member. Your posi unit could fetch as high as $300 cause they are hard to find, even in the after-market world.

Trees
 
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