for a marine diesel is priced anywhere like the one I bought for my car- OUCH!!! I would definately find a generic one to fit from Larry's or Jims guy. I got one for my old Pathfinder from a fellow in California for a fraction of the VW price. Worked great. Most of the good shops seem really knowledgable and are able to rebuild to change the amperage to suit within reason. IIRC mine had the guts of an 100 amp Mercedes alt stuffed in the case to fit.