Have to agree, quite common. The regular cab is the standard but it does seem more of lately are extended cab and crew cabs.
Anyway, no kit is made and the only resin I found was the emergency crew cab truck and they wouldn't sell just the cab. Although diecast this might be the easiest way to build one in 1/25. F-350 extended cab 4x4 dually. Looks pretty simple to remove the back doors.