if your looking at a short box ready fw ( where the fw pin sticks out in front of the upper deck) then add 3.5' to your current length and if you buy long box required fw then add 5' to current length. this should get you close to your current overall length of tv and tt combined. btw the fw tows sooooo much better than a tt, I've had both and wouldn't go back to a tt personally. I have a long box dually and my 295 wp's fw pin sticks out past the upper deck which imo is short box ready. I can turn 90* to the fw with the truck, haven't found a spot I can't get in yet but not looking for one either lol.