We generally frown on allowing customer supplied parts due to the inaccuracy of fitment. Also warranties cannot be honored. We have a warranty arrangement thru our parts suppliers that does not cover independent/customer supplied parts. There is also a chance if the part is incorrect, a disassembled vehicle in one of our working bays can tie up a technician that could be working on another vehicle. Some classic/hot rod vehicles require non-factory special equipment parts and some allowances can be made.