Anyone pull a 14k 5er with a gas engine

As long as your comfortable hearing that gasser pulling really high rpm's (sometimes 4-5k) on hills, climbs, and headwinds, yup, it'll do the job. A diesel will do it with less strain on the engine, tranny, and your senses. I'd guess you get about 6-7 mpg's pulling 14.5k with a gasser.

FWIW, a Ram 3500 6.4 gasser is rated to pull 16k or so with the 4.10 rear end. Payload for a Ram 3500 SRW is at least 4,000 lbs.---considerably higher for the dually.