I have a 1990 Fj62 and i recently rebuilt the t-case cause it was leaking t-case fluid into my tranny and i didn't drive too long with it like that or atleast till i figured it out. And here lately i have hear a whining sound but very low. I use to have a 60 it an sounds alot like a release bearing or throw out bearing going bad. But i haven't have any issues with slipping or anything. She drives great but i just wanted to know about that sound. It happens once the truck is warm. If i switched to synthetic fluid would that help some?