2002 Monaco Diesel

I have borrowed a 02 monaco diplomat 40 footer and the friend that loaned it to me wants to sell it to me now for N A D A book value with a diesel generator with 50k miles and 250 hours on the generator what can I look forward to in terms of problems or things which may need attention right away has not leaked and a pressure test was done with no bubbles. I have driven it 500 miles parked it and no oil leaks beneath the generator, or engine there is some seepage around the driver side rear jack. If I purchase it I plan to scrape old caulk and caulk everything weekend after next. I have owned a truck camper and most recently a small class " C " this appears more involved than a truck camper. Thanks for any information or suggestions you can provide.