About 3-4 months ago I swapped the 47re out of 96 12 valve for a nv4500 (2wd), everything went relatively smoothly and the truck drove great. 4th gear would grind going in unless I shifted nice and slow but other than that I had no complaints. I used a luk clutch with valair hydraulics and a trans out of an 01. About a week ago I was driving home and when I went to shift into 4th the trans seemed like it was stuck in 3rd and I really had to pull to get it out and into 4th (grinded bad going into 4th too). since then I parked the truck and now I can't get it into any gear unless I do so before starting the truck. when I go to put it in any gear; it grinds like I'm not even engaging the clutch at all. Ive looked over the hydraulics and they seem to be fine so I'm not really sure whats going on. Im thinking something clutch related or maybe TOB? I plan on pulling the trans this weekend for new sychros, updated main shaft, and input shaft(slight play when I installed it) but I'm looking for some insight as to what (or where) to look for the problem so any 2 cents is appreciated!