serveral people including me were concered with the depth of the gm 900 platform trucks for us fifth wheel camper pullers well they really look deep i went and measured them the old truck (800 platform ) is 20" deep and the new truck(900platform) is 21" deep it is only an inch myself i could not belive it it looked 2 to 4 inches different to me but the tape measure don't lie i will get one now that was my only consern with the new truck .

Dont know actual depth from rail to floor but the height from ground to top of rail at tailgate was 58 inches on the 07.5 I measured compared to 55 inches on my 07 classic.

that differance would be the 07.5 has 265/70/17 tires and that will raise it the dually on the other hand will still have the 215/85/16 which most of the rv pullers have the over all height will only raise a 1 1/4 over all on the other have most people are concerened with the inside bed height with the hitch hitting inside and messing up the bed my truck allready sits higher because of my weld 17" wheels but the overall height will change on the 2500 but not the 3500 dually only by 1 1/4 higher