The bezel is glued. Some have a tiny bit of threadlocker, some have a lot. They are gluing a lot of their newer lights. Not the GT, though. It’s just really tight.
TA did not build this driver. It’s based on his Texas Avenger design, though. It is a proprietary driver and not sold seperately. You really don’t want it. If you want a good FET driver for e-switch use, Lexel is the best source. He is moving a bit slower right now due to a hand related problem, but will probably be back to making drivers soon.