The DRW will really help with pin weight and stability. My guess is you are over GVWR with the 5er, passengers and stuff. Many say the 250 or 350 SRW does just fine but having owned both i'll never go back to a SRW for towing. If it were my money I'd look around for a DRW with the 4.30 rear end to get the additional towing capacity since my next trailer will probably be heavier. The 4.10 loses 2500lb of towing capacity to the 4.30.
Also I'd go straight to the source for tow and load specs if it wasn't on the vehicles door. As far as I can tell the tow ratings are near equal for both vehicles all things being equal (4x4, c/c etc):
http://www.fleet.ford.com/resources/...TTgdeSep08.pdf for tow ratings.
https://www.fleet.ford.com/truckbbas...0-450_08bb.pdf
Hybrid Mode
