1991 Chevy S10 4.3 V6 4WD. I drive daily in 2WD, the shifter will move to 4 high, but takes a TON of strength to move it. Also, I cannot engage neutral (transfer case) or 4 low unless the truck is off. No matter where I put the shifter, I have no power to the front wheels.....

Btw, this is my first good-sized vehicle, learned on a 3 cyl 5 speed Geo metro loved that thing.......

 

93 S-10 Blazer 4x4 diagnostics... - Car Forums and Automotive Chat

 

does it help to shift at a slight roll?

 

I figured out that it will shift when the transmission is in neutral... but I can't tell if the front axle is engaging