? on 7 1/4 to 8 3/4 rear end

There are many posts on this, so search.

Pretty sure the driveshaft will have to be cut, which most drive-shaft shops can do fairly cheap.

I kind of recall the later slip yokes have different splines, so if you are changing the tranny you need a later yoke.

If you are keeping the 66 tranny, you need a spacer ring for your smaller torque converter snout to fit in the 360 crank hole.