Diesel Bombers - 4l80e transmission wires got chewed up

Just bought a 95 6.5 3/4 ton diesel & it was advertised as having a bad tranny, wouldnt go into 3rd & overdrive.........When I looked underneath the truck I seen that the wires that plug unto the tranny somehow fell onto the front driveshaft & chewed them all up.So I had a extra wiring harness from a 99 & cut the tranny plug off & wired it up & got it to shift into all gears but now it won't go into reverse. If I unplug the tranny it will have reverse so obviously I have something wired wrong & the 95 had a few different color wires than the 99...... Can anyone chime in on how to wire this thing up.... Your help is greatly appreciated , thank in advance