to tell the gear ratio, there should be a tag on there somewhere that says what it is. If theres not then you could get an estimate by seeing how many times you have to turn the driveshaft for the wheels to rotate 1 full time...if it takes 3 times, then you have a 3.00 gear.
Pull the hub cap/center cap off the wheel. Look at the center opening of the wheel at the axle. A 31 spline axle will have two holes about 1/4 inch in diameter. A 28 spline axle has what looks like a hollowed out area at the end of the axle but no holes.
.....you don’t have room to move the rig, here is another way to do it. Instead of pushing the rig just jack up on rear tire and rotate it one full turn with vehicle in neutral. Count the number of wraps and times it by 2. The total is what you use to figure the gear ratio. Note this procedure will only work with open diffs.
If it came out of a 65-70 Mustang is is a 28 (not so sure about the big bodies). To my knowlege FoMoCo did not put 31s into any passenger cars during that era, but all large bearing 9" axles had the 31s (trucks/vans/broncos).
If it came out of a 65-70 Mustang is is a 28 (not so sure about the big bodies). To my knowlege FoMoCo did not put 31s into any passenger cars during that era, but all large bearing 9" axles had the 31s (trucks/vans/broncos).