rear end help

This is one of my first of many major projects on my mustang. This car has been somewhat of a mystery due to the fact that it was a originally a 6 cylinder, transformed to a v8. A 302 @ that?!? My rear end started to make grinding noise. It seemed fitting since the rear end is a 6 cylinder rear end. Just bought a rear end from a 67 gt mustang. Oooookay. I am still a veritable rookie compared to you giants. So your experience and knowledge are very valuable to me. My questions are...

1) If they swapped it to a 302, did they have to swap the tranny too? If so, what types? The car is automatic.

2) Would they have to replace the driveshaft as well?

3) If not, even though my rear-end going in is from a v8 67 mustang, will my driveshaft be the right length?

4) If not, how should i measure it to be sure? Do I have to just do it and see?

5) I am trying figure out exactly what kind of rear-end I have. The data plate is gone. The only thing I can find is some faded number casted in the rear.
It say 4025-a which I have done some reserach and I think it's a war case. But I don't know. It's a lot deeper in the back that the 6cylinder rear, but from the shaft to the u-joint area. Plus it have three visible dimples in the back area.


Thanks guys!!!

Thanks for a fast reply!!! Luckily I was smart enough to go for the five lug. I know better, thank goodness. Unfortuantely, it does not have the obvious trademark, 9 inch hump in the center. Just a huge dome with three dimples in the back.

I have 3 dimples on the dome area (is that considered the front or the back???), one on the left, one on the right and a small one in the middle. The filler plug is on the other side on the back, not on the side.