I’m actually a mechanic in Sudbury Ontario Canada..
i leave for trade school in Toronto in two weeks and I have limited time. I was really hoping the 18’ would fit. My boss has the software to flash anything if needed. I’m glad at least any 6l80 until 14 works then. That gives me a few more options.
And as for your question of HOW it blew, it started off no reverse when hot. Now I drive and if I get it hot enough it will get locked into 2nd gear and just rev up. I’ll have to pull over let it cool and then limo home.. and when it does this. The manual-/+ does not work.