I got stuck as hell this past weekend because I thought my 4 wheel drive was working and it isn't front differential won't engage some reason. 4x4 light comes on in hi and low and when I get under truck to see if front drives haft is locked in it is I'm so lost someone please help. Need 4x4 for work

 

Quite possibly you have a broken front axle engagement fork. Not certainly, but very possibly if all else checks out. Seen 'em on eBay for under $50 if you can do the work.

Have someone engage 4x4 while you are underneath and watching the shift lever- make sure the vacuum system is working. If not, I replaced my vac system with a cable system mounted inside the cab.

Couple ideas for ya.

 

Where would you buy those parts if it happens to be broke I just have a funny feeling it's the vacuum actuator like you said -___-

 

Personally, I get all my parts off eBay for usually a fraction of what they run at a parts store or the dealer.

 

It might be an easy fix, with mine the shift lever near the vacuum actuaor was moved out of its slot, everything was working, it just wasnt engaging because since it was moved out of the slot the fork could not actuat, moved it back into the slot and wallah it was fixed, welded the pin in place where it is attached too on top so it wouldnt move forward out of the slot again, works great now

 

A couple trucks I was looking at buying had that problem, I think it was the transfercase? idk tho

 

had this problem with mine also. Had vacuum lines get a hole in em and wouldnt engage. you can manually engage the front dif by moving the lever yourself. try engaging the lever yourself and see if works. if it does its something vacuum related. if not then its the shift fork.
if it is a vacuum problem it could be the vacuum lines, actuator on axle, or the solenoids on the firewall. If you need any more help pm me and ill do what i can to help you.