1991 k2500 5.7 tbi My trans is about to drive me nuts! I was on my way to work this morning and it wouldn't shift into third gear. So I pulled over and checked the fluid, it was good. So I played around with it and noticed that when I put it in D that it won't shift into second but if if put it in OD it will shift into second, but not third. Its like its a gear behind. When its in OD it shifts fine from 1 to 2 and don't slip or anything it just won't go into third. What is going on!!!! I came home and changed the filter and fluid. I didn't see anything in the pan, just a few specs of what looked like dirt or just trash. Filled it back up, no difference. I'm guessing its shot. What do you think?