Unfortunately I have tried the seats from a GM truck and I don't think they work to well. I still have them in the motorhome but I feel they're too big. I am definitely going to replace them with something different. In my case I had to modify the seat base which wasn't that difficult.
I visited the AS factory and saw some seats I really liked and asked where they got them and they said Villa International http://www.villainternational.com/products/seats.htm
but they are pricey. Way pricey. But man do they look good.
I don't know if the captains chairs from a GMC Savana are smaller than the driver and passenger seats, if they are these look real nice. Attached picture is from a 2006 GMC Savana. The only problem is they don't have the integrated seat belt, but they do have 2 armrest which I like.
Flexsteel makes some real nice seats also just haven't been able to find a website that shows the different styles and pricing.