ok so i bought a 76 grand prix off of one of my dudes. the car itself is a wreck but it has a good motor and tranny which is what i was after..its a pontiac 6.6liter 400 with a 400 tranny. i have my 81 cutty with a V6. i want to drop that 400 in my car and my question is do you think i will have to get a custom length driveshaft for this? Also do you believe that i will need to use his rear end or will i just need to gear my stock rear?