I pulled the cover off because I couldn't find the axle housing stamping and the numbers on the ring gear are 1356151 14 39. My calculator says that's 2.78 but the service manual says 2.73 only for the A bodies, the B bodies had a 2.78. It's no big deal, it's not posi and it has a pretty bad clunk in it when I turn either drum so I may look at my other differential to put in this one. It's probably the same thing, I couldn't see a stamping number on that tube either.
You can put any Pontiac 10 bolt 8.2 gears into that housing. Buick did not have 2.73 gears till 1968 10 bolt 8.2 rear. We have posi units for that rear gears rebuild kits etc. Even NEW axle shafts. If you need any help or prices just PM - Jim JD
I have at least 2 that I'm scrapping. I was going to start taking them apart tonight. I don't know exactly where you are but I'm 45 minutes SW of Chicago oFF of Interstate 80.
Geez how much for the rears? Wish I was closer... Need all the cores we can get and your scrapping them. Jim
Update: My '64-72 GM parts catalog lists the 64/65 rear differential case assembly non-posi all as p/n 1358752, ratio 2:78 so I guess that's the one I have. Another update: I found it, group 5.579, o/n 1396800, ring & pinion set 2.78 ratio 39/14 teeth which is stamped on the ring gear. Now I know what I have and it is original. Somewhere in this forum I read that a TH350 trans has a low first gear which will help it take off better, is this true?
th400 is 2.48 first gear th350 is 2.52 first gear 1.76 1st gear in alot of the 2 speed auto trannies so any 3 speed tranny will have a MUCH better first gear launch and the reason for the 2.78 2.56 gears . 2 speed cars usually had a 3.08 rear end gear same as the 6 cylinder cars ---------- Post added at 04:35 AM ---------- Previous post was at 04:33 AM ---------- Yes . BUT you also need the correct carrier . carrier breaks are as follows 2 series carrier 2.56-2.78 3 series carrier 2.93-3.23 4 series carrier 3.36-4.33 - and beyond. What do you have now you will need to be in the 3.36-4.33 range to use the 3.73 for the 65 rear end IF you are not you will need a 4 series carrier. Jim J D
