i have a question with my rear end on my 95..

[eddielugnutz]

the 8.8 and 7.5 are easy to tell apart, from underneath the car looking at the differential cover, a 7.5 (or 7.8 as you put it) will have a shape more of like a rectangle, with two flat sides top and bottom while the 8.8 has a more round shape with all sides of the diff cover being equal in length with a more of a square or circular shape. All v8 mustangs 86 and later got the 8.8, sorry dude, I think you have the 7.5, the axles are interchangeable being of same spline (28) and dimensions, but who cares, you should always get new ones anyway, but just in case yours are in better shape than some junk yard rear you pick up, you could use your axles.
The 8.8" is a mean rear, a dime a dozen, and easy to swap.
Hope this helps.