Ok to clarify, the LQ9 is from an escalade, trans is from the van.
Sounds like using the original harness with mods is an option with the 4L80e, and $30 for ecu (I'll assume $60
which is not as bad as I thought. I think I'll see if this guy will deliver and if so pull the trigger.
TBH I've been looking for an entire vehicle so I could snag all the bits and pieces including seats, but I've had an eye out for about 6 months with no luck...