Ok fellas/fellets. I currently own a 1987 Chevy C10 pickup. Just rebuilt the 350, and now the tranmission has descided to act up. Momma always said honesty prevails so here it is. I'm dumb or was at the time. The transmission was already shifting hard and i descided to fool around one night in the mud. Upon leaving the are i realize the transmission will not leave 1st gear. Bye the way it's a TH700R4. Reverse still works. Symtoms include. Accelerates but upon releasing gas pedal acts like its in neutral. If hammered on at this point drops back into 1st and so on. Will not leave first gear. I have pulled the transmission out of truck and was going to order rebuild kit and voyage on but figured I should ask for tech help first. Any hints or procedures to fix problem would be greatly appreciated.