Not sure exactly what you want to know. Most DP's are/were made on either Freightliner or Spartan chassis. Exceptions were the Monaco coaches made on their own Roadmaster chassis and Country Coach on their own Dynomax chassis. There are differences, for sure but I would focus on finding a coach that has been well maintained and has a floor plan and features you want. The more entry level coaches were usually built on Freightliner XC with smaller engines with rear radiators. The mid to higher level rigs were generally on Spartans with side radiators. Monaco and County Coach used their own excellent chassis as does Foretravel.
My personal recommendation is to define your budget then look for the higher end used rigs that meet your needs and fit your budget.
This may help some:
Motorhome chassis comparison
