7.5 rear end

I am new to the mustang sport and I have a 79 mustang with a 7.5 rear with a 2.? gear. Well I was told that a 4x4 ranger or bronco II with a 7.5 should have a posi rear and should have a lower gears. I was wondering if this was true and if the gears will fit in my mustang with out a problem.

im not sure about the 79, but i know the 87-93s had 3.73s in the 7.5 rear.

Don't bother with swapping gears. It is expensive to set them up properly as it must be done by someone who knows what they are doing.
The 7.5 rear end is a little weak for serious work. Mustang 302's all came with 8.8 inch rear ends stock from the mid '80's onwards, with reasonably decent gears. They are cheap to buy and plentiful. Find one and swap it in. You will end up with a much stronger unit

7.5 rears aren't worth the gear oil that comes out of them after 100,000 miles.

but in all seriousness, if you're gonna make this car fast, change that axle as soon as you can.

and by the way, 'posi' is what comes in a chevy. 'traction-lok' comes in fords... saying posi in this forum can get you shot :naughty:

im not sure about the 79, but i know the 87-93s had 3.73s in the 7.5 rear.
I'm not too sure about the 3.73 option, but it's possiable. Here's a copy from a post a made a few days ago for you to reference.

Through out the years 79-93, 7.5" rears had many options.
2.26(79-80)
2.47(79-81)
2.73(79-93)
3.08(79-93)
3.27(83-93)
3.45(79-93)
3.55(84-94)
These were options on only "open" rears.