The air compressor is made by Gast, more of a commercial unit. It has a pressure switch that goes on at 85 and off at 105 I believe. The 'relay' that runs the power to the compressor is a 200A rated (silver contacts) continuous rated solenoid, fed by a 100A breaker. The air tank (cheapo for airhorns from ebay) is between 1 and 2 gallon and hangs under the cubby in the bed on the driver's side. The air line is dot with push-on fittings and is 3/8" dia. The air compressor rattles a bit since it's mounted to the plastic bin behind the seat- I might run some self tappers through it all to hold it tight to the back wall of the cab.
The batteries are Odyssey PC1200LMJT- Got the "L" for left positive so with my arrangement I didn't have to move/splice the positive lead at all. I made a frame for the two out of 1/8" angle iron and used riv-nuts like the ones that come with weather guard boxes (a dealer who sells weather guard boxes will have a ton of these laying around and the little install tools too)- 5/16" flat head screws hold the battery box in place. Another one of the 200A continuous rated solenoids connect the two batteries. The switch on the dash labeled BAT runs the dual battery circuit the same as a painless wiring dual battery kit. The dual bat gauge is from Kussmaul- they make electronic stuff for fire engines and police cars mostly. Since I haven't mastered the posting pics thing yet still, I'll just attach some pics again!:smilies27