The Thor Super C on the F550 chassis is a budget RV and they left all the extra options off of the truck chassis/engine combo. When I looked at them they only offered one cab interior color whether it matched the coach interior or not and it was basically a work truck cab.
I have an F550 chassis by another manufacturer and it came with the Lariat Crew Cab, however, when my coach was new it was at a substantially higher price than the Thor is today.
Now, you have 2 choices in the aftermarket, not sure if you can buy an OEM exhaust brake kit for that chassis engine combo or not. I have a BD Diesel Performance exhaust brake kit on mine and Banks offers a system as well. Mine works great, it is all plug and play because the VGT Turbo is computer controlled. A mechanical baffle in the exhaust system could damage the VGT turbo. Hope this helps
2008 Host 300 Super 'C'
2008 Ford F-550 Chassis
Diesel
4x4
Lariat crew cab
20' enclosed car hauler/garage
'87 Jeep rock crawler
Turbo'd