No ATF has "lifetime" service value. Changing your transmission fluid, and your brake fluid, yearly, is the only way to ensure a lifetime of service from a lifetime truck.
There was a time when I didn't believe either statement was true. The...
In that case, transmission fluid is a 'lifetime' fluid. The maintenance schedule only asks for inspections every 40k miles, which is not good enough by a long shot. I drain and fill mine at 50k which seems to contribute to the transmission (and...
Sounds like you are fixing things for no reason. The only thing I’d do on your list is serpentine belt. Fresh fluids throughout and keep going.
Google Waddington Effect
I want to do more research into this, but the welds almost look bronze/copper in many places. I don’t think it’s surface rust at the outset, but perhaps something from the welding process itself? It does seem like the paint has a hard time...