Gap or no Gap?

[Dodger]

Ok, I have read a lot posts on this forum and can not find an answer. Is it better to bolt the cab to the box (like it is now on my E350 rig) or have a bellow seal and a gap? I will be replacing the E350 with a much Larger F800 or 4700 sized truck. The box is only 11 feet long, if that matters.

[geofkaye]

....use the bellow seal....bolting the two together will cause one to rip apart the other at the joining surfaces as the frame flexes and twists... geofkaye