I have a 1983 Trane gas furnace, Model BLU108E936B1, the pilot light went out, I could get it to relight but wont stay on> Changed the thermocouple, same results, Pilot light doesn't look right as I recall before, the flame doesn't seem to come up as high as before to hit the thermocouple correctly. I tried different positions for the flame to hit thermocouple but still same results, Pilot wont stay lit.
I would still not trust the thermocouple. I encourage you to just take the new thermocouple back out, and re-install it. I had this exact same problem and unfortunately paid a contractor to come out and do just that, and somehow it fixed it. I guess the things are just finicky.
There should also be a way to adjust the pilot light's flame, typically a screw.