Anyone out there have the part numbers for the 4:33 ring and pinion set for 1970 GS? I wanted to verify the set I bought decades ago from the dealer. Pinion gear is stamped with 9A39 GM DA 230119 247 Ring gear 9A39 GM PC 234
On the ring gear, the numbers 9 and 39 are the key. Divide 39 by 9 and you get 4.33. The 70 used the Buick 8.2 10 bolt, and parts for them are harder to find with less aftermarket support. If you bought them from the dealer decades ago, I'd say they are right for the 70 rear. Are you sure you want 4.33 gears though?
For the 1970 Buick 8.2" the ratios and part numbers are as follows; 3.91:1 (43-11)__1394472 4.30:1 (43-10)__1394306 4.78:1 (43-9)___1394307 My parts books don't list a 4.33:1 as an available ratio from Buick. Pontiac 8.2" perhaps, but I have no Pontiac parts books to verify it. Hollander manual lists a 4.33:1 (39-9 combination) as available on Firebird through 1969, and Tempest/GTO through 1972.
These may be a set of Olds (BOP) 4.33 gears that fit 65-67 Buick rears. If so, they may not be the same as the 68-70 Buick 8.2 gear sets. Notice the book for Buick 8.2 rears 68-70 uses a 43-10 tooth count while these are 39-9.
Thanks for the info. More mystery for something that has just been hanging around the garage for years. I bought them in 79 when I worked at a Buick/Pontiac dealer in Rochester MI. The parts dept was cleaning house and the sold them to me at cost because I has a GS and they wanted them out along with a few other GS items I bought. Counter guy was sure they were from a Stage 2 package, but you know how stories get spun. Never installed them, too steep for the street. I was hoping to do something next swap meet I can get to. Looks like some more research!
My 66 Olds parts book shows a Group 5.529 gear set for a F85 (A Body) was #9780492 with a (39:9 tooth count) 4.33 ratio.
Best way is to show some pictures and give some diameter dimensions. The inner bearing surface for 68-70 will be 1.875 and the spline count will be 27 for the yoke. Jim
