What is involved in swapping a 5.3/4L60E to a 6.0 LY6/6L90E in an NNBS truck, and what are the common gotchas?

Here is what the documentation says. Each point links to its source; details depend on your exact computer, harness and transmission.

• The T43 is the internal transmission control module mounted on the 6L80E/6L90E valve body; removal uses external Torx Plus bolts with an E12 socket, and the module unbolts from the valve body with 11 bolts. (D9I5Ve8F04Qxt)
• PSI's instructions require sending the removed T43 module along with the transmission's four-character ID tag, where the first character identifies the model year. (D9I5Ve8F04Qxt)
• PSI's HAR-1098 standalone harness covers 2009-2015 LSA engines with 6L80E/6L90E transmissions and an E67 ECM, with a simple four-wire hookup for engine and transmission conversion. (Gearstar)

Confirm against the instructions for your exact parts before wiring. More: Transmission control in our tuning guide.