Can anybody decode the gm rear axle indentification code that starts with "JUG". I've looked at a ahlf dozen decoder sheets and its not listed. The gears are8.5 inch 255's w/posi and were manufactured in NOV '74. I've been told this is a 69 Oldsmobile rear, but it measures exactly the same as a 75 Nova. The gearsets appear interchangable in every way, except that 69 Oldsmobile gears are supposed to be to be different(nobody lists gearsets for the that year olds)
I assume it's a leaf spring rearend? I don't think there was a leaf sprung Olds. in '69. From the date on the gear, it probably is a 1975. Wasn't the Olds. rear a 10bolt cover with 12 bolts on the ring? Also, I've always known that (2.55) as a 2.56 gear. As far as the "JUG" goes, I don't have an answer for that. Sorry.
unfortunatly, this carrier is in a street rod, and I can't tell for sure if it was originally a leaf spring or coil spring rear.
Well, it seems apparent from Ricks post that it is indeed a '75 rear. And FWIW, I got my numbers backwards on the '69 rear info. They have a 12 bolt cover and a 10 bolt ring gear that is NOT the same as the 8.5". I had to call my Olds. buddy after my previous post to check my facts.
thamks for that info. I knew something was screwy when both diffs measured the same. Next dumb question: can I use the posi from the 255's with a set of 342 gears. The things are supposed to be different, but I have enough shim space to use the posi carrier(its only about 1/4 in bigger than the non post carrier). Also, I've heard that Mr Gaskit makes some kind of spacerthst allows you to use the smaller ratio posi with the taller gears
The Jalopy Journal
