I'll pass on what little information I can about lift gates. I currently have a Maxom rail gate with 4,000 lbs. capacity. The rail gate requires swing doors as the rails are welded to the sides of the box. The unit I have is quickly removeable (with fork lift or crane) and stored until needed again. The rail lifts interfere with the hooks at loading docks, making it impossible to hook to the ICC bumper. I do not believe that any of the Big 3 docks will a truck with this gate to be loaded/unloaded at the dock.
I suspect that another driver can comment about that.
The other type of gate available is a tuck-under or fold-under, which is what you see on most of the trailers/trucks. However these lifts are generally smaller platform and less capacity. The tuck-unders can require that the ICC bumber be removed to accomodate the lift. I have seen trucks where the ICC was modified to be removeable and then reattached using pins.
My lift was installed by Mobile Refrigeration (Detroit) 313-272-2600.
This is a large lift, for my specialized equipment and was purchased and installed for about $11,000. I would suspect most lifts would be in the $4,000 to $6,000 range.
I am planning to have my truck & lift at Woodhaven in August for the Expo.
Drive Safe