EDIT: truck is a 1989-4cyl-manual hubs

Got some snow last night and i locked in my manual hubs and after i had gone about a mile i needed to shift into 4-hi. When i pulled back on the shifter it would just grind and not engage, after coming to a complete stop it did finally engage but was hard to go in. so after a bit i took it out of 4-hi to see if it would work again and no go only when i stopped. so engaged it into 4-hi again and die-engaged on the fly and i could hear a awful whining noise that wasn't there before (sorta sounds like a gear that was not fully engaged) so i quickly pulled it back into 4-hi and the noise stopped and the 4x4 stared to work perfect....any ideas ? could it have been due to the cold temperatures? it was 18 degrees when i pulled out.

highway

 

did you try shifting into neutral try that and see if that will shift better thats why i do on a personal note i beilve it is better for the t case and tranmision

i hope you get it figured it out

 

yeah tried with the tranny in neutral....same results grind sound

 

check the gear oil level in the t-case. If it's low it'll have trouble shifting

 

I went out this morning and tried and it worked perfect 4hi and 4lo, hope it was just the cold

highway

 

it could very well be. synthetic will work better at low temps. It's still worth checking the level.