is there an easy way to unlock the front hubs so that one can have low range in 2wd?


I realize they are vacuum actuated, so how can I supply vacuum to the hubs while switching to 4-low to keep the IWE's disengaged?


reason for asking:
I backed my camper into the shed last night and that requires backing up a steep(ish) hill while turning sharply. In 2wd you have to use a TON of throttle to back up the hill and I'm always afraid of overheating the torque converter or transmission. 4-low makes easy work of it, but even on the grass the driveline bind is troubling. in the old plow truck, I just unlock the front hubs and use 4-low, but I didn't want to unhitch and rehitch to use the old beater so I just used the expedition. I had plenty of traction in 2wd, but I really had to lean on it to get it to back up the hill.


any ideas?

 

Here's a visual of what I'm talking about. (please forgive the crudeness)


the red lines represent the door location and the yellow lines show how I have to back a trailer into the shed (Tow Vehicle path). it requires a lock-to-lock S-turn and a correction to get the trailer and TV lined up to back straight in to the shed. there's just enough room to go from sharp jackknife to get the TV back in line with the trailer before you hit the shed in front of you. for scale the building is 50x80, so there's just a bit more than 50 foot between buildings.

 

Use a 12v normally open solenoid valve in-line with the front hubs. When de-energized they will pass vacuum as usual, but energized them and they close, then you can shift into 4Low and vacuum never reaches the hubs. Here is a sample valve: