How hard is a 4L60-to-6L80 swap on an NNBS truck — what parts are actually needed?

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)
• On 6L80E swaps the TCM sits inside the transmission, so factory wiring and harness connections clip back into place with no special external controller. (LSX Magazine)

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