Battery light wont turn off

Could be a problem with the computer controlled of the field generation of the alternator but did you use an AC Delco unit? cheaper alternators are bad right out of the box. Here is a guide to see if it is charging.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Please run down this guide and report back.

There's no way to diagnose this without standing right by the truck and doing some tests, but given the combination of symptoms, you might follow the smaller battery positive wire to where it bolts to the under-hood fuse box. Be sure that connection is clean and tight.

It's much less common but also follow the smaller negative battery wire to the body and be sure that's rust-free and tight.

The next thing is easier to do than to describe. It involves connecting a test light to various places, then watching whether it goes out or not when the problem occurs. That allows you to narrow down where you're losing voltage and where you're not. A common problem that could be found this way on older GM vehicles had to do with their use of aluminum wire. The connections where they were riveted to the brass strips in the fuse box would corrode, especially when they stuffed the fuse box right above the driver's feet where road salt could reach it. I haven't heard of that problem in many years, but that's the type of thing we would look for.