It is going to be very hard to lower your F-450 as it has a mono beam front axle even if it is 2wd so you have very little room to lower the truck from the start. To lower it 6" would most likley require a whole front end transplant from either a F-350 or a chevy 1-ton. If you are going to go that far use a chevy front end and lay it all the way on the ground
