After mine got done it still pulled to the right. I'm going tomorrow to get it redone.

 

Have the shop check out the rear end. Sounds like your axle shifted. If your axle shift it will throw off the whole aliment. I would look for lose U bolts, broken leave springs, shackles, and bushing. A good aliment shop will can tell in the if your rear axle is out of whack.

 

just checked under rear end and noticed that the bottom leaf on the stack on the drivers side is shifted by about 2inches. but the other side seems straight.
something aint right lol
im gonna take and have it looked at for sure
also noticed that my muffler may be on backwards.
its a stock muffler and it says inlet with the arrow pointing towards the engine not the back of the truck. not sure if it is pointing to the port that is the inlet or if it is the airflow direction.

 

Sounds like your center bolt that holds your leaf pack together either sheared or rusted off.
Your muffler is installed correctly. The arrow should point towards the engine.