Help with a measurement please

[ryanroo]

I am getting ready to install the gooseneck turnover ball hitch in my frame and i need a bit of help. i think that i remember the wood bed was all but right on top of the frame rails at the kick up above the rear axle but i don't know how far above the frame the metal floor is.

Can anyone with a steel floor bed pull a quick measurement from the top lip of the frame rail to the lowest part of the bed floor ribbing?

Thanks

Ryan