I took my 2007 Diplomat (Cummins engine) down to Gilroy Kenworth. They work on Cummings and CAT. They took over the old Guaranty RV facility in Gilroy. They were HAPPY to work on the coach, and I was in and out quickly. There is also a truck stop there with diesel and a truck/RV wash on the back end of the building. RV's are $1.50 per foot, including the roof. They did a good job and it is nice to have a clean coach, again. Gilroy Kenworth has been open for three months and it is very easy to get to. It is on the back side of the Shell station. Kenworth, the RV wash and the truck stop all share a large parking area, so you could probably boondock overnight if you needed to.
Gilroy Garlic USA RV Park is two miles North at the next exit if you need to stay overnight.
http://www.gilroykenworth.com/
5870 A Monterey Rd
Gilroy, CA 95020
Phone: (408) 754-4000