From the FFR forum:
"I purchased a new TKO600 for my build. These transmissions are quite stiff to shift when new. They are shipped without transmission fluid so you need to keep that in mind. Initially when I tried running though the gears, the shifter fork got stuck and the transmission would not shift. I called Tremec and they told me to take the shifter plate off and check that the shifter sliders are properly aligned for the shifter fork lever. you may want to call them or search the net for proper shifter alignment instructions. As it turns out, the Tremec tech was correct and the transmission shifter sliders became misaligned with the shifter fork. I believe (if memory is correct - several years ago now) I had to manually align the shifter sliders so they were in a straight line (neutral) and I inserted the shifter fork and reinstalled the shifter plate. I used a slot screw driver to carefully slide the shifter sliders back the the proper neutral position (aligned in a straight line from left to right).
if your shifter lever can move from side to side and when you turn the input shaft the output shaft does not move (you may need to hold the output shaft to keep from rotating) you are in neutral and there is no misalignment. if as you describe, the shifter moves side to side but when rotating the input shaft the output shaft moves in the opposite direction, the transmission would seem to be in reverse - suggesting the shifter fork is misaligned with the shifter sliders - similar issue as I had."
This is an easy fix - good luck!
Watch this video.
http://gtamc.com/showthread.php?1434...ear-(Fix-video)