Considering purchasing a 2003 Monaco Diplomat 40 PWD

wyolincoln wrote:
...but with Monaco being belly up, don't want to end up needing a widget that only they made. That too would be bad.

Monaco is not belly up. They were purchased by REV group along with Fleetwood RV, Holiday Rambler, American Coach, and Renegade RV.

https://www.monacocoach.com/

You may want to contact them to see what they may still support for parts from prior to their bankruptcy.