Been years since I did one, but yes there are rebuild kits available for them all. All new solenoids, etc... Can't remember the price, but it wasn't outrageous IIRC. (was on a Cummins in a Freightliner, got them from Cummins) Martin
jake tune up kit to suit mod. no. 340c/d or e is all the same P/n 143-6628 you should be able to get it from a Cat dealer