A 2000 Dynasty is a good coach. There's not a whole lot of things that you need to worry about, but its 21 years old.
The Cummins ISC of that vintage has a fuel delivery system that is susceptible to catastrophic and expensive failure if it develops a leak. Many have no issues and some have replaced the stock lift pump with a FASS or similar pump. Do a search for FASS in this forum.
Other than that, the Norcold 1200 is a fire hazard if the recall hasn't been done on it and maybe even if it has. A residential replacement is popular.
Some people have replaced the stock Shepard steering with a TRW and report it makes a big positive difference.
All the systems are 21 years old and can be expected to fail at some point. I'm in the middle of a total rebuild of my slide out. I've rebuilt the three hydraulic cylinders and am replacing all the hoses. I've replaced both AC units, the inverter, the refrigerator, propane stove and both air horns and have plans for a new hot water heater and microwave.
Have it inspected by a RV inspector and a heavy duty truck shop. Look for signs of a leaking roof, soft floors, wall delamination, just like with any other RV.
Dennis and Katherine
2000 Monaco Dynasty