I think you did OK.
Don't worry about the transmission. Take care of it in accordance with manufacturer's recommendations, or your own schedule, and all should go well. About 2010, GM made changes to the TECHM - that's the major transmission modification.
I'd suggest browsing Crutchfield's site to see what's available in audio components for your car. You want to make sure everything will work with any mod, i.e. chimes, turn signal sounds, steering wheel controls, etc.
Good luck with the Enclave. Have you joined that forum, too? There's probably more make/model specific info not covered in this site.
2007 Acadia SLT-2, 'HiYo' Silver outside, Ebony/Titanium inside, no NAV, no HUD, no errors
Last edited by speleos; 05-19-2017 at 07:56 AM.