I don't know if this is the right forum or not, but I'm looking to buy a 69 GS 400 in which the rear was changed. The original rear should have 293 gears, but the owner tells me it was replaced with a GM corporate rear with 343 gears. I understand the ratio principles, but how will this affect the performance and function of the vehicle and are there any potential problems to be considered? o No:
If it is a true corporate then it is a post 70 8.5 rear and not a 68-70Buick 8.2 rear. It will not be as good for gas mileage and will in my opinion not be pleasant for road trips. It may be a few 10ths faster in a quarter mile.
Gear ratios aside, it's might be worth pointing out that the corporate 8.5" rear is considerably stronger than the 8.2" if strength is of any importance. Devon
No numbers. Just look at front of pinion flange/u-joint mtg area. Does the pinion flange have two 7/16" headed bolts retaining a stamped steel strap on each side ??? If it does, the A-body rear in your '69 is an 8.5. All different 8.2 rears, most (but not all) 12 bolts, & the '67-70 type "O" Olds 10 bolt, all used U-bolts, lockwashers, & nuts to retain the rear u-joint. This is easiast way to spot the '71-72 8.5 A-body hsg, as there were 3 different 8.5 A-body hsgs & only the most common version will have pics on the internet Got Posi? :3gears: Roger
Well I checked the car out over the weekend. I didn't see any straps or bolts so I went thru some paperwork with the owner and found a receipt for a used 8.2 GM A-body rear put on the car back in 2000. So the corp-rear claim proved wrong. I have the GS Facts and Figures book and want to check for codes next time I see the car. I know it's not the original rear, but I want to know which it is and have an idea what the gears are.
If you remove the rear cover and read the numbers off of the ring and pinion gears I could tell you or you could count the teeth on each.
Jim, I don't think the owner will mind removing the cover, but is it necessary?I thought I read in GS facts and figures the axle itself is stamped with a code. And this references a specific rear and the actual gearing. No? Maybe I could ask the owner to check for a code and send it to me?
The stamping on the axle tube may or may not be consistent with what is in there. So if you really want to know you have to take a look.
Didn't have the opportunity to remove the cover, and couldn't find a legible # on the axle, but the receipt from the shop that installed it in 2000 says Chevy 8.2 with 3.08 gears.
