ok, once i get my paycheck this weekend, i want to swap my stock muffler for a force muffler from summit racing (its basically a knock off flowmaster with better build quality so i hear from my mustang buddies) my question is, what are the stock dimentions of the muffler?

also, i have an open diff, i really want a detroit true trac but cant afford the $420, is there a GM posi i could get? what about welding the rear end? any sugestions

 

Welding the ring and pinion makes it a locker. That has to be cleaned cleaned very very carefully so there is no oil left on the gears, welding with oil left, it has a high chance of catching on fire. Personal experience. If the rear axle didnt' come with positrac, then you need to change the ring and pinion too. I'm not sure about the stock diemtions of themuffler ether.