P.S Floor Fanel/Transmission Hump Grind

[standclear]

Ok heys the story, i just got my truck all back together from swapping cabs and heads studs. I started the truck a couple of nights ago and let it run fior an hour and it was fine, no noises or anything. I took it out on the road for the first time tonight, after about 10 min of soft driving i noticed a very faint grinding sound when cruising around 50kmh coming from the passanger side floor panel/transmission hump. so i turned around and headed home. On the way home the sound got progressively wrost. got home checked everything, climbed under and everything looks good. i let the truck cool off and took it for another ride, once again started fine drove fine for ten or so min until the engine got warm then the noise started again. i crawled under but i didnt find anything loose, cab mounts tight, tires not rubbing on anything, exhast is mounted good and not hitting my firewall, the truck starts fine but im going to pull the starter tonight and check it, but could it be my torque convertor? whats else do you guys thing it might be?