I am installing a 1990 TPI motor into my 57 chev 2 dr 150 sedan. The wiring harness that I need from Ron Franciss needs my rear end ratio. Is there a way to get the rear end ratio with out removing the pumpkin? I have heard you can turn one wheel 360 degrees and count the drive line rotations and then divide by some number to get the rear end ratio. Thanks, Harold Pickett

if the driveshaft has to be turned 3 turns for a full 360 degree rotation of a tire, its a 3:1 ratio. mike

The 1955-64 has the diff. number STAMPED into the front of the center carrier casting, right side, in line with the outer axle tube. That number will ID the original ration. Not completely for the carrier/ring gear and pinion to be exchanged from a different car but the number would still be correct. Very seldom was just the ring gear and pinion exchanged for a different ratio on these models.