a 904 is light and strong enough to hold power. people will say you need a 727 but ive run a 904 into the 10's consistantly with no problems for 4 years. 8 3/4 rear would be best but they are hard to come by these days for an a body. i did just see one for sale around detroit or somewhere with a 318 and 904 for $300. dont remember if it was this forum though.