Hi, I'm looking into a 5.3 drivetrain swap once it warms up.. The local "you pull" yards have engined with all accessories for $140, and all trans are $80. So given I find a decent drivetrain and yank it all. Will the ecm still need re-flashed because of removing all the un-needed plugs?If so will a gm dealer do this because I live 3 houses down from a large dealership. Thanks