So I'm new to this forum but not new to Ford, I have a 2002 SVT Lightning and a 2009 GT500, just ordered a 1976 F150 with a 360CI FE Big Block in it, 4 Speed TopLoader Transmission. Can anyone tell me if I can tell what gears are in it, what is the rear end size, how many splines are in the transmission? I would like to know because I bought a 428 Cobra Jet from my friend who builds racing engines and I plan on putting it in the '76 F150. Thanks

 

Best way is to drop the driveline and count splines, rotate the pinion flange and count its turns versus wheel rotation.

 

I had a 1975 F150 with a 390 and AT. When my pinion locked up in my rear end I replaced the 3rd member. It had a tag stamped 3.00 31. Found out it was a 3.00 ratio with 31 splines. if the rear end hasn't been messed with (which is impossible to tell) it should have that tag. To the best of my knowledge they had a 28 spline and 31 spline rear in the mid 70's 1/2 ton trucks. Again, that's saying nobody has changed it. lol. A lot of racers used the 31 spline axles and cut them down for drag racing apparently. I agree that your best bet is to pull an axle to count the splines. Than the ring gear should at least have a stamp with the ration if you get into it that far.

 

If its the original rear it should be the 31 spline 9 inch
In my opinion the best rear end ever made as far as the ratio, without the tag you just meet to jack up 1 side and count the revolutions of the tire vs the pinion
But a 9 inch should handle that 428 with ease