nv4500 help.

I'm in the middle of a nv4500 out of a 95 5.9L 3500(gas motor) swap into my 98 5.9L 1500. I thought it would be nice to have reliable tranny in the truck. The 46re wasn't working for me. I got everything swapped over and the truck running but I can't get it into gear while its running. If I shut it off and start it the truck creeps forward. I have a brand new clutch set, clutch fork, fork pivot, and retaining spring. I had to buy a 98 master to fit the firewall but bought the 95 slave not knowing the 95 slave is different from the 98 just like the master. I've. Pulled the trans twice and double checked my work and its fine. I'm going to try the 98 slave tomorrow but if that doesn't work could it possibly be a bad pressure plate even though its brand new? I don't want to pull the trans again but I need some ideas. Thanks everyone.