Just replaced all my synchros. 1st and 2nd gear seem normal. Reverse a little hard to get into. 3rd, 4th and 5th lug the motor down. In neutral the truck wants to go backwards. Are the synchros (brass) just hanging up ?? I have had the trans. completely torn down twice now. I have not actually driven the truck yet, just checked each gear enough to make truck move.

 

https://www.dieselbombers.com/diesel...ssion+problems try this thread and see if it helps if it dont we will try another option https://www.dieselbombers.com/chevy-...html#post94186 see if this helps too

 

GOT IT!!!!!!!! Had one to many shims. Which made everything just a little to tight. Everything would spin before, but everything spins alot more free now. Truck drives, shifts great.

 

good deal glad you found the problem