Mile High wrote:
The manufacturers don't give a rats about noise. It's the availability of the chassis that dictates the outcome.
X2 Tooling around the block on level ground during the sales process doesn't expose any noise issues. By the time you find any noise issues, it's a done deal.
Rear engine chassis are mostly based on tour buses which only come in diesel flavor. They also tend to be bigger and heavier with higher tow ratings, favoring diesel. Plus if you are dropping a quarter to a half mil, you want to be able to brag about the diesel.
Front engine tend to be low to mid range units where cost is more of a consideration ($10k on a $300k unit is a 3.3% up charge. $10k on a $100k unit is a 10% upcharge) and most chassis are based on gas engines. The house is also built around the gas engine specs and dimensions. if they have to put in a diesel, it has to fit within the same envelope since with Class A, the RV manufacturer builds the doghouse. Plus modern gas engines are both powerful and long lived, so it's a tough sell for not a lot of gain.
This isn't like pickups where they sell by the tens of thousands and if they can sell even 10% with diesel, they are selling many thousands per year.