i just divided 65 by 17 and got 3.82. Is this what you meant ? It seems odd that the rev's at 70mph using this transmission was over 3000 when others were reporting lower figures than that with a 3.82 FD. that's why i assumed it was a 4.06. Any advice ? ... G.count the number of teeth on both the ring and pinion gears and do the math is the only real way unless they have part numbers stamped on them somewhere.
yes, thats what i meant by the math. I would also double and triple check your count on the ring gear, as its pretty easy to skip a tooth or count one twice.
what size tires do you have on the car? with 215/50/16s the 3.82 FD at 70MPH should have the RPMs about 2800-2900.