I contacted Tru-Glo about G36 TFO sights (tritium/fiber). There response was they don't make them for the 36.
I put a set on mine anyway! Had to do some minor grinding of the front sight screw to keep it from interfering with the barrel. Just gently ground down the top a couple thousandths or so. Used a stone. Put some locktite blue on and put it together. I've shot about 500-600 rounds with it so far and no issues.
BTW, the rear sight went in just fine. They are absolutely awesome (especially for tired, old eyes like mine!)
The model number I put in was TG131GT1.