How can i figure out what my 9inch has in it?

[stephen4785]

Im getting a 9inch rear end from my buddies 71 F100 or F150(cant remember). At first he told me it had 3.70 gears and a limited slip but now he cant remember if its a 3.40-3.50 or 3.70 ratio. Oh and now he doesnt think its got a limited slip in it.Its a stock rear end. Anyone if theres a tag on it or what the stock 71's came with? I know I can turn the yoke and count how many times the yoke turns to 1 revolution of the tire but I dont have the rear end yet.

 

[6Stang7]

Post the tag #, that is the best I can do for you.

 

[302 coupe]

if you remove it you can easily tell. Count the teeth on the pinion gear, count the teeth on the ring gear. # of ring gear teeth divided by # of pinion gear teeth will be your ratio. You can also tell if its a trac-lok or not. If the ring gear bolts are countersunk, its a trac-lok, if not its an open diff. Might as well count the axle splines while you're in there.