I know this must have been covered at some point, but I was curious regarding the available optional rear gear ratios. In 1970 it was listed that a 3.91 gear set was available on the GS as code "OZ". Earlier cars listed gear sets as low as 4.30 "OT". Is this similar to the Olds 3.91 "OZ" rear end? Was this part of the Tow Master option on the GS 455 Order Form or part of the Trailer Towing Option UPC #G50? How many documented cars were ordered this way? Was this also available on the base GS (350) car? Would this be an SCO car or is that only for body oriented (Fisher plant) options rather than mechanical oddities?
Scott, the deepest gear the factory would install on a 1970 GS Stage 1 non AC car was the OZ 3.91 posi axle. It is the same axle housing as any 3.42 or 3.64 Buick 8.2 housing in 1970. In 1970, 45 1970 GS/GSX Stage 1 hard top cars and 2 1970 GS Stage 1 convertibles were factory ordered/built with OZ 3.91 Posi rear axle code G9. All of these cars were obviously factory non Ac cars.
I do not. I have two very mint "O N" rears. One that is the original from the Reynolds car with the original 4.78's that Pop and Jim installed that are chipped beyond use. I am cleaning up and restoring that rear housing. It is super clean as it more than likely never saw rain and has probably less than 1,000 miles on it since Dave Johnson took it out and shelved, and put the current 12 bolt in it, That I restored and put back in for now. (car has 1,676 original miles total). Since then I've located another super clean "O N" that came out of another Buick race car and was taken out for a stronger rear back in the day. That one has a good set of Buick 4.30 gears in it. The plan is to use the 4.30's in the original Reynolds rear. Interesting thread. I never knew of the rare OZ 3.91's...
So it looks like 45 GS/GSX Stage One hard top cars and 2 GS Stage One convertibles were ordered with the OZ option rear end. I think I've seen here that the standard rear for the GS455 4-Speed was the 3.42 open with the post being an option, but what about if the car was ordered with the performance rear axle - would this be a 3.64 posi? In other words, did you have to have a Stage One car to order the performance axle options (i.e. 3.64/ON or 3.91/OZ rears) or could you simply order up a GS455 and select the 3.64 or 3.91 rear?
Scott you are correct, in 1970, a GS 455 standard no cost HD 3 speed on the floor and M21 Close ratio Muncie 4 speed GS 455 came standard with a 3.42 open axle. With these cars you had to order the posi with G4 option ( Positive traction differential) then you recieved OO code 3.42 posi rear axle. If that same GS 455 manual trans car was ordered with G1 (performance axle with positraction) the gear ratio went deeper and moved to the standard non AC GS Stage 1 3.64 posi axle ON code axle. G9 3.91 posi OZ code axle is not on regular car order sheet, a dealer would have to special order it. I have a no option, ie manual steering and brakes, no ac, no vinyl top, no wheel and tire option, 70 GS 455 4 speed car ordered with G1 3.64 posi axle. Describe your car, color combo and option load.
Hi Rich, Numbers engine, trans and I 'm pretty sure rear end. The car is a 19 A color combo with a 185 bucket interior and no console 4 speed, manual steering, Power drum brakes, no a/c, no tire option, but not sure on the wheels as it shows an "A" under "Wheel Covers" on the build sheet . As far as options, it has the sonomatic AM radio with no rear speaker and the U9 instrument group with rallye clock. Not sure on the axle yet as I still need to find the code and there is nothing on the build sheet found on the gas tank (flint car).
Thanks for the image Cork - looks like you have the 3.91 based on what Rich is saying. Did you also have the build sheet for your car, and if so what was on it to indicate such an option?
The build sheet only had a"P" under options the tires were" B" 14" H-78 white walls under whlcvr was "1" hubcaps standard. Best advice send your info to Duane Heckman he can decode it and give you a report . The money I paid to decode info on my car was worth every penny and put more pieces in the puzzle of its life. Also look for the body production final usually stuffed behind the driverside upper air vent rolled up and stuffed in mine had paint overspray from the dash it hid it well.
Thanks Cork, I'll contact Duane and have him look it over. I see a "P" listed under the "P/T" section as well and when turning the wheel one rotation the yoke goes over 3.5 turns, so I think this may be a 3.64 rear. I'll have to do some cleaning on the tube to see if i can find the stamped code.
