Hey Nick,
16 Tahoe 6L80. Was rebuilt by a GM tech 2 years ago. Had an issue not going back to 1st when you come to a stop. Intermittent. Also didn't always engage in reverse, also intermittent, but reasonably often. Also, after it was rebuilt, it always shifted funny...almost like a stick from 1-2, it stop accelerating almost like you were shifting a stick.
I'm a dealership vendor, water leaks/sunroof, etc. Had a former GM tech that now works at a Ford dealer look at it. Changed fluid/filter. There was a bit of glitter on the magnet, not awful. He removed and cleaned out the TCM and reset it.
Worked perfectly for a good long while. Didn't do that shifting glitch anymore, and still doesn't. But now doing the not downshifting into 1st at stops thing and slow to engage in reverse. Intermittent as before. Works fine otherwise.
It was rebuilt with what I assume was stock replacement stuff from Transtar. I replaced the same trans in my 15 truck 6 months ago with one from a buddy's tranny shop. It is beefed internals, billet converter, so I guess all improved stuff that normally fails.
Thinking I may have to do the same with the Tahoe, or let it go be someone else's, lol. But we like it.
Would you concur that it's on the road to ruin once again?