I've got my eye on a 2003 420DA that's about 3 hours away from me. It's on it's 3rd owner, and started out as a freshwater boat except for a couple of years in Florida. It has the Cummings 6CTA 8.3 engines (1100 hrs) and an Onan genset (1300 hrs). As a complete neophyte to diesels, are there any "tell-tale" signs I should look for on a first look-see visit. Naturally if the stars align correctly, a full engine survey would be a must. I have asked about things like if A/C units have been replaced, refrigerators replaced, and when (and who) has serviced the engines/genset? Any other things I need to put on my list of things to check? About the only things I've gotten from the broker is it had a bottom job done last year, and "it shows real well."