Does 2:1 mean anything? The shop guy said that's the number of rotations to drive shaft once he got it up on in the air...
No not sure how he would come up with that. 4.11 gears would be one complete turn of the tire would make the drive shaft turn just a little over 4 turns, 4.57 would be 4.5 turns. I guess there's a chance someone put 3.50 gears in, but that would be 3.5 turns of the driveshaft.
On another note, if there's any chance that it started out in California, the only two DSO codes for California in 66' was for Los Angles and San Jose. DSO codes 71 and 72.










