Does anybody remember the formula for rear end axle ratio. My numbers matching 1970 SS 396 Camaro L-34 was given only one rear axle ratio 3:31 to 1. I have the original 14 x 7 rally wheels silver color, the tires are Firestone Firehawk Indy 500 225-70-14. The diameter is about the same as the F-70-14 Firestone Wide Ovals which is 26.3 inches. The Engine, TH 400 and rear axle are original, but I do not know if the gear ratio was changed. When I take it out for drive on the Highway at 80 MPH the Tachometer reads 3,750 RPM. That seems high for 3:31 to 1 gears. I have two floor jacks, but do not want to jack up rear and measure how many revs of drive shaft for one revolution of the tire. If I can get the formula I can see if it does have the original rear gears. Thanks John.