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I have 2 Posi units, 1 in a housing with 4:11 gears (AP -16-66), another empty housing which shows AU 3-7-66 3:36 housing, and a posi unit I do not recognize or at least it doesn't look stock to me. The case is different, much thicker, notched out for heavier springs. Any input or identification is appreciated.
Reference attached photo's
Marking on gear.
What I believe to be a stock posi unit. This the 4:11 unit AP 16 66.
Last edited by c66vet; May 8, 2022 at 03:12 PM.
Reason: sequence of text
As mentioned, the posi out of the diff is a 63-4 DANA vette posi and they are really not good. Many failed in use, the 63-64 gears were also not good. They were replaced in 65 with the Eaton posi which is what is in the diff in the picture. That is a 4 series case which uses a 4 series gear, for the past 20 years 4 series gears were made by US Gear to fit a 3 series case but those are gone now.
The housing is a wider one, typically that started in 67 but some 66 may have received the revision. Those bearing caps were used from 65-71.
The parts of the DANA and Eaton are not interchangeable. 4 series gears are harder to find and those cases will only work with those gears, not a big demand- unless someone wants a 411 or 456 diff and has NOS gears.
Thanks for the replies. I thought I found something going through all my accumulation of C2 Corvette parts. The older unit looks stronger beefier, thicker gear and springs. Who knew, it pays to ask and take advantage of the wealth of knowledge on this site.
Posi Unit Identification
