Being a 2001, those units are already 12 yrs old - you may get 15 yrs out of them, they could go 20, unfortunately there is no way to guess. I would call Dometic with your model #s and they'll cross those over to the low profile units - they can even equip them to work with your existing thermostat setup. They are excellent to deal with. After replacement list them on Ebay or Craigslist and you could probably get a couple hundo for them.
94-Newmar Kountry Star 40-KSDP
Spartan/Cummins 8.3C-300HP/Allison 3060 WTEC-II/25yr RV Tech RVIA Certified/Onan-Cummins Certified