A 6L60E transmission in a 2003 Tahoe? Are you sure on that? Maybe a 4L60E transmission? That trans would have been typical for a 2003 Tahoe and as far as I can tell, GM never made a 6L60E. The 6L80E came out in 2006 and it could have been possibly retrofitted to a 2003 Tahoe with a 5.3 liter but you won't find a stock 2003 6L80E BIN mated to a 2003 engine. That combo did not exist in 2003.

If it is a 4L60E that you have, there are several combos with richly detailed XDF files around here for 5.3L engines and 4L60E transmissions. Basically, you would completely overwrite (after making a copy) your 12582607 BIN and replace it with one of these:

12208322

12212156

12202088


Rick