newbie needs help on 91 4x4 jimmy

[tlracing]

I have a 91 jimmy st, 4.3 v6, auto. My problem is when in 4whd right front wheel is acting like its locking up, any insite on my problem

[Sparky2263]

The rf axle is the one the slip collar engages to drive the front axles. Ck. out the pic in this thread;

http://www.s10planet.com/forum/showthread.php?t=4930

[tlracing]

what would fix this problem

[89VORTEC]

Check all of your vacuum lines. One line runs from under the battery box to the transfer case. The other line runs from engine vacuum to the transfer case.

These lines go to a 3-port (3rd port is vent i believe) vacuum switch in the top of the drivers side of the transfer case. These vacuum switches are the most common problem on the s-trucks, aside from broken or eroded vacuum lines.

It almost sounds like your front diff. might be disengaging intermittently due to vacuum loss to the actuator servo under the battery box.

If you are positive the wheel is "locking up", then you could have internal differential problems, but check everything else first.