Ok i broke the imput shaft in my tuck so decided to rebuild it right with billet shafts. 3disc converter and full rebuild kit from georend. I put the trans in the truck today it goes into gear but barley will move foward and backward. Feels like its slipping big time. do yall have any ideas what the problem could be?

 

add more fluid, once you start it up the converter takes up alot of fluid, make sure you check it while it is running

 

It sounds like a fluid problem to me too. Did you fill the converter before you installed it?