I have a 2001 33 footer, 20,500# Ford chassis with the V-10. 53,000 miles and nary a problem. I wish I could say the same for the tranny.At 27000, the front seal went bad....$38 for the seal kit...$800 labor. I had to replace it at 48,000 with a JASPER re-manufactured. So far, so good.
But seeing you asked about the motor, at 30,000 I replaced the anti-freeze, hoses and belt. Looks like next year I'll be doing that again at 60,000. The motor pulls my "toads" (I have 2) without my even knowing they are there...I get 7.3 mpg pulling a toad and 7.8 not pulling a toad.
My opinion is that the V-10 is bulletproof.