i have a 92 and the tranfer case goes in to gear and spins but the hubs dont lock in or ingauge i had the same problem on my old truck an it was the vacum lines are the blazers vacum hubs or are they electronicly powered thanks

 

Vacuum.

On a 92, I believe the vacuum actuator is on the passenger fender. A vacuum line runs from the engine to the transfer case vacuum switch, then back up to the vacuum actuator which pulls on the engagement cable running to the front axle. Inside the front axle, there is a shift fork that pulls a collar over the passenger side axle to engage it to the differential.

The most common problem is a faulty vacuum line, followed closely by a faulty vacuum switch, faulty vacuum actuator, or a frozen cable. It is not unheard of for the collar inside the axle tube to break or round off the splines making it very difficult to engage.