its a long story. ok my buddies 98 z71 5. 7, he went to put it in reverse on the opening morning of deer season and it started making noises but no movement. he did still have 1st and 3rd but no OD and 2nd. after searching for a few days i found the sunshell to be the likely problem. so we decided to pull the tranny from the truck and tear it down and sure enough the sunshell and sunshell gear were stripped out, so we orderd some parts. deluxe rebuild kit 180$, beast sunshell 75$, sunshell gear 20$, transgo seperator plate 15$, i also found the 3-4 accumilator piston pin was missing 18$, and the 1-2 accumilator spring was busted 20$,
i cleaned it all up real good, installed the updated pistons and new clutches and followed the atsg manual and several postings off the net, tore the valve body down and cleaned it , greased it and meterd out the solenoids except number six because it is not in the book but i have found it is the tcc solenoid and should not cause my problem. did not rebuild the pump but did replace the gaskets and orings, i figured it worked fine before you know.
so now all back together reverse works great, the sunshell did the trick and second, OD work great. but when setting still when you shift to OD or 3rd it labors a little but dose not fully engage in first, if you give it a little gas it barely moves forward. if you put it in second it will start out in second, if its in 1st it starts in first but slips a little. when its in OD or 3rd it flt like the band might be holding so i double checked the servo assy and it seemed awfull dry, not much fluid in it.
when you drive down the road manually shifting through the gears it shifts strong and runs great it seems, kicks down good, downshifts good, tcc apply works,