Towing my new 38RSSA

4.10 gears and factory air susp. Towing that heavy, the gears will allow the engine to not work as hard to get things moving. Yes you may not get as good of hiway mpg's, but I'd sacrifice the hiway mpg's with the amount of weight you have/will be towing. Ford has used air susp for many years in their Lincoln Town Cars w/o a problem. Semis have air susp as std equp nowadays. I wish other OEM's would offer it as an option on their pick-ups. While I don't agree w/ pick-ups towing 30-40K (IMO that's MD truck territory), you have to remember that all that weight has to be stopped. Yes, brakes are on both truck & trailer, just an awlful lot of weight to be stopped by an electric brake system (just my $.02 here).