i have the 3100 ss version and its on a ford f-450 chassis with a 5000 lb tow capacity. they also make them on a chevy chassis but they only have a 3000 lb tow capacity. my ford has the v-10 triton engine that tows my car with no problem. mileage is 7-10 mpg depending on terrain and speed.
The E450 has a Independent Front suspension using twin i-beams and coil springs rated for 5,000 pounds. The rear uses a Modified Dana 80 (modified as in wider than normal spec) with airbags over leaf springs and is rated for 9500 pounds. Both axles have sway bars, however the rear sway bar is under-sized for a larger Class C body (it's more appropriate for a typical cube truck body). The airbags on the rear axle are installed by Forest River.
Gross Combines Weight Rating for the E450 is 22,000 pounds. Most RVs are hitch-limited.
2000 Ford E350 DRW Wagon (14-pass all captains chairs)
V10 w/ Banks PowerPack, Diablo Predator, 4.56 LS, ~350,000 miles
New Desert Fox in the works!