have a 74 ford think someone changed rearend to 1 out of an auto gears don't match need to know a good way to tell what ratio the front is to get the rearend to match
You can count the number of teeth on the ring and pinion gears. # of teeth on ring gear divided by # of teeth on pinion gear = gear ratio.
You can put the vehicle on jackstands and rotate the driveshaft and count the number of rotations of the driveshaft it takes for 1 rotation of the wheels.
You can look for an ID tag on the axle, but that may not be accurate if someone changed the gears and left the original tag.