I'm not sure if I'm posting this in the correct area, but here it goes.
I've read a lot of issues that others have when their 4x4 is not working and its usually based on the vacuum.
On my 2001 F350 7.3, I flip the switch to high and I can feel something happen. It feels it might engage. But I don't get anything when in low. I've done it at a stand still and a slow roll. I need that low to help reverse while pulling my trailer. Any ideas why I'm not getting Low?