4x4 Not engaging
 

Looking for help with 4x4
I have a 91 B2600i ex cab. When I engage the 4x4 by pulling the lever back, the 4x4 light comes on in the dash but the RFW switch does not light up and 4x4 does not engage. Put the truck on a little hill that I have climbed in 4x4 on my other B2600 and the front does not pull. I know the transfer case works because I can put it in 4 low and the vehicle drives in low. I have switched the RFW switch, solenoids near fuse box both with parts from a known working vehicle and nothing. I have 12 volts on each solenoid, 6 volts on the top two from what I can tell.
When I pull vacuum lines off each the top two, they have plenty of vacuum, can both hear and feel it, the bottom two that connect to the engage and disengage has little to no vacuum comparably. Not sure if that is normal.
I connected a vacuum to the actuator under the truck and watched it move when I applied vacuum from a brake bleeder, did not move much, but I am not sure how far it actually does.
I have not replaced vacuum lines and feel that may be where to go next but my local parts stores do not have any and it will take me a few days to locate. I have looked the lines over and did not notice any tears, breaks, or soft spots. Had a local shop look at it and they came back with nothing.
I appreciate any ideas or thoughts on where to go next.

To help further diagnose, I have jumped each switch under the truck to bypass the switch, Still nothing. Replaced 4x4 cpu, switched individual solenoids as well as ran power straight to the solenoid, nothing.
I guess the next question that someone may be able to answer is, Can I bypass the 4x4 system and connect another switch either for power or to engage solenoids. Perhaps leave stock system in place, connect another toggle switch inside the truck to give the solenoid power, run a vacuum from the manifold straight to the actuator with a solenoid in between to cut vacuum when not in use. Toggle switch gives disengage power when in 2x4 and engage power when in 4x4 and basically delete the rest of the system.
Any suggestions?