hey fellows, i hope i am in the right place if not please redirect me. my question is.. will a riviera 10 bolt 3:42 work in a 72 gs 10 bolt?
The Riviera uses the 9 3/8 rear. Completely different than the 8.5. If he has 9 3/8 3.42 posi, that is worth some money. They don't make anything for that rear.
thanks guys for the info. i am not sure what riviera 10 bolt it is.the guy that was telling me, doesn't know anything about it either. i was wanting to buy it if it would work in my gs(that is if it were a posi trac). i wanted to make sure it would work before i talked to him any futher.
Find out which rear it is. If it is a big car 9 3/8 3.42 posi, and you can get it for cheap, you can sell it for a profit. BTW, you can get whatever you need for the 8.5 10 bolt in your 72. Aftermarket support for that rear is plentiful.
There is a 2 letter code on the bottom of the left axel tube if its a Riv 9 3/8 rear. That code will tell you and us what gear it is and open or posi. If I remember right PY is the code for 3:42 posi rear on the Riv
Of course, one call always unbolt the ten bolt rear differential cover like I just did to change out the factory fill differential oil. I figured it could use some freshening up after nearly 43 years of the same oil.ou: Sure enough, when I unpried the cover, I seen that my 1969 Riv was just a one wheeler with the standard 3.08 to 1 ratio. The original papery thin gasket was still there. I took me two hours to carefully scrape off the most of the gasket, but I did not quite remove it all which leads me to the next story. I bought a differential cover gasket from AutoZone. Unfortunately, they sold me the wrong FelPro part number for the 8.2 differential for the Skylarks and the Gran Sports. Turns out I could not find the Buick 9.375 differential cover gasket with 10 bolts anywhere in town. So back to AutoZone I trudge to refund and return the incorrect gasket. Felpro makes gasket material that YOU have to measure and cut yourself, just like the old timers who cut gaskets from brown grocery store paper bags. I also bought some silicone gasket sealant just to make sure. Well I carefully traced out the outer gasket edge with the differential cover and cut it out. I then poked the bolt holes with a pencil and then measured about a inch in to cut the inner part of the gasket. I also had to cut the gasket into a bottom 2/3 and a top 1/3 since FelPro did not make this square peice of generic gasket large enough. Finally, I drilled out the bolt holes. I sparingly spread the silicone gasket sealer on both sides of the gasket and proceeded to rebolt the cover. After waiting a few days for the silicone to cure, I refilled with Mobil One 75W90 gear lube and then my heart sank as I seen tiny drips of nasty, smelly, gear oil dripping into my hair. I was so annoyed, I just rolled the old girl back into my car port and threw some oil rags under the "pumpkin" to catch the oil. I try again a week later and proceed to unbolt the cover. Turns out I missed some old gasket, but the silicone cured long enough to stick to the old gasket and strip it all clean! I have enough of the generic FelPro gasket left to cut a new gasket and liberally apply the silicone this time. This time, I let the silicone cure for a week and refill with gear lube. I think it is holding as I see no leaks. I tried to read the stampings on the bottom left side of the axle tube, but they are so faint, I can only read D 009. When I double check two more times for leaks, I will take my trusty wire wheel drill to try to document the numbers. By the way, I know somewhere in quite rural northern Minnesota where there is a 68 Riviera GS with a posi. It needs alot of work since it is a North Dakota car with the obligatory road salt cancer. It is very difficult to find Buick 9.375 posi's these days! I would sure love one for my Riv.
I snapped some poor quality pics of my 9.375 differential, but they were blurry and very dark due to poor lighting, so I just deleted them from digital camera. Several weeks ago, there was a nice stickied thread about the 12 bolt Buick 9.375 differential with the 10 bolt cover and all of its variations. Sure would be nice to have that returned.
I believe that all 68/69 Rivi GS's came with the 3.42 posi 9 3/8" rear so if you find one, sink your teeth into it and dont let it get away
they were suppose to, mine sure didn't 3.07 open, I'm on the hunt but out of cash so it'll have to wait
I have a 66 posi unit for the Buick 9 3/8 rear. Might get used on the 67 also. But i think it was 66 only HARD to find posi unit. NOT cheap either all reconditioned and ready to go. No bearings included as they are old...we can remove them. THIS unit was only used ONE year and has the same size bearings on the carrier unlike 68 69 70 with larger driveside bearong and smaller passenger side bearing for the carrier (posi or open ) Jim
