LED Upgrade for GLOCK Tactical Light GTL-10 GTL-11 GTL-21 GTL-22 GTL-51 GTL-52 | eBay
GLOCK GTL 21 & 22
found an LED replacement for Glock GTL model flashlights/combo lasers. It works great and it's just a drop in upgrade (link in the comments) : r/ Glocks