No doubt it's getting difficult to find the Chevy chassis for larger Class C's.
In September of last year, we looked at Sunseekers (Forest River) class C's on a dealer's lot. The 31' models were on the Ford chassis. Our 2015 we purchased used, is a 27' model (actually almost 28') that we selected because we liked the leg room in the passenger area in the Chevy chassis and my DW won't drive the Ford. We had a Roadtrek class B years ago on the Chevy chassis that she enjoyed driving. DW says it feels just like the Roadtrek we had in the 1990's. (Happy wife, Happy life). The 4500 chassis is fully adequate. It rides nice and pulls a toad fine. We enjoy the rig a great deal. Where we live in FL now, there's a Chevy Car/RV dealer. Most Class C rigs for sale there are Chevy's which is quite convenient for maintence purposes.