i have a 94 chevy 2500 can anyone tell me why when shifting from 2wd to 4wd high the transfer case grinds and will not go in but it goes in when stopped

 

Do you mean 2hi to 4hi?

I don't understand it either on my truck... It'll shift on the fly so long as I keep the pedal at the perfect point where it is neither accelerating nor coasting. Kind of like trying to slip a vehicle in gear without a clutch. Small margin for error.

I've not had a 4x4 with shift on the floor before other than my Isuzu Trooper and it was a 5spd.

 

Thank you for the info i will try that