Just follow the vacuum line from the pump to the firewall then across the firewall. If its not obvious hook a gauge to it and go from there

 

went and glanced with a flash light, looks like its very possible that its a vacuum line, I'll look into it tomorrow when its light out

 

Pretty simple really. There will be some lines going to the transfer case from the firewall and a couple from the transfer case going to the CAD unit on the front axle. I'm betting one of those got knocked off. There is also a line that goes to the Vacuum solenoid under the drivers battery and one that goes across to the passenger side and into the cab to run the A/C controls.

 

Fixed, thanks guys. It was a vacuum leak.