get an 8.8 swap, theyll last longer. i learned this turbo coupe thing from someone on stangnet, sorry i cant give credit personally, but go to a junkyard and find a ford turbo coupe, it had an 8.8 rear end with 3.55's (stick) or 3.73's (auto) and while your in there you can grab the rear axles and disc brakes for a full rear end upgrade, all parts for easily under 350 bucks.