Chassis ID

I have a 1986 Gulfstream Class A with the Ford 460 driveline. I have searched and Googled everything I can to find out which chassis this is built on. I have all of the ID and VIN numbers, but there seems to be no way to cross-reference. The wheel base is 160 inches. I thought I might have a John Deere chassis, but where Deere normally puts the ID number I found a Ford stamp with E7 US 8312 AA above it.
I would like to know the chassis ID when I need parts, it's the first thing they ask. Any ideas?