Allen,
The last service truck that I put together I used a Champion compressor with a 13 HP Kohler motor, 30 gal tank. I paid a little over $2000 for it.-
http://www.industrialaircompressors.biz/page/958176
It was recommended to me by a company that I highly trust and they used them on all of their service trucks. The compressor worked flawlessly for me (ran the crap out of a 1" impact).
I just spoke to the above company again, and they are now using an import compressor called MI-T-M on their service trucks. It is powered by a Robins/Suburu motor, sells for ~$1900.
http://www.mitm.com/series_details.a...oductLine_Id=2
Whichever way you go, make sure to order the flex pad feet kit.