When I try to shift into 4 low in a 1995 H1 I get a loud squeal and grinding sound. I'm in N and stopped when I try to shift. I now have to turn the engine off and then shift into 4 low inorder to engage. Do I need to lubercate the shifters on the Tcase? Any ideas? Thanks.

 

Is the truck on a level surface? The shift to low should be a strong, continuous motion. It is normal to hear a pronounced clank or thump as you drop it into low.