GoldOlds

Does anyone know what gear ratios were available for the '69 Cutlass Supreme with TH350 and 4bbl 350? My car has 3.73 gears in a Chev 12 bolt, which I suspect is NOT original (not that I'm complaining).
Thanks!

- GoldOlds

Redog

Do you still have the RPO tag in the trunk?

GoldOlds

Afraid not. The main reason I suspect the gear ratio is not original is the spedometre/odometre. They're slightly off. But then again, the rear tires (255/60/15) aren't the original size either. The rims LOOK original, but I think the originals were 14", NOT 15".

- GoldOlds

monzaz

probably a 12 bolt olds rear was the original or 12 bolt chevy if it was Canadian car.

12 bolt olds 2.56 2.78 3.08 3.23

12 bolt chevy 2.56 2.73 3.08 3.31

Doubt it was anything steeper than that. ONLY the high performance versions of your car would have 3.42 3.73 3.55 3.90 etc.

12 bolt chevy rear look at the passenger axle tube between the spring perch and the center section casting on the front face of the tube.

there should be some letters and numbers stamped into the tube that will tell you the original ratio of that axle housing.... In the cast webbing of the differential you will find the date code the housing was cast also, letters and numbers again BUT cast into the housing NOT stamped.

example B 23 9 (Feb) 23rd 1969 cast housing.

example of axle tube stamping ccw 0230 B

J-(Chicago)

those are some pretty meaty tires for a 69 cutlass

GoldOlds

Yeah, those tires alone provide more traction than the car actually needs (for now at least). I put the rear end up on jackstands and did the ol' "turn a rear tire one full rotation to see how many times the driveshaft rotated" test. It was roughly 3 3/4 times (although that method, of course, is not an exact science). It IS a Canadian car, with the tell-tale "upside down V" on the diff cover.
Thanks for the input, everyone!

- GoldOlds