i just went out and took a tape measure to it and it's right about 7" but at the moment there's no motor in the truck so i'm gonna say 6" normally. I'm also running all-pro shock hoops. I did look at marlins kit and looks like they go with 12" unless specified so i'd have to guess you'd be safe with 12" shocks as well.
I'd say with the motor it would be more like 5"