Race Idiot
I've seen the one with six wheels once, I think it was an SVT model. But i'm assuming that's not an F150.
Edit: Nope, didn't look like that.
Right - the six-wheeled ones are F-350 Dually (dually as in dual rear wheels) models. To be perfectly honest, they're pretty rare even in the states. There's three main grades of F-series pickup.
First, you have F-150. That's the most popular, by very far, and is offered in regular cab, extended cab, crew cab, flareside, styleside, long bed, short bed, 2WD, or 4WD trims plus a combination of most of those. Truthfully, there are probably 50 different F-150s on the market when you factor in trim levels (XL, STX, XLT, Lariat, FX4, and the luxurious King Ranch which I might buy if not for a lack of side airbags) not to mention engines, of which there are three available (202hp 4.2 V6, 231hp 4.6 V8, 300hp 5.4 V8).
That's your basic 2004-present F-150 XLT extended cab flareside with the short bed and 4WD.
These are rapidly becoming more common - this one's a 2004-present F-150 XLT crew cab styleside with the short bed (actually you can't get the long bed with a crew cab) and 4WD.
This is the 1997-2003 model, likely an XLT or XL, with an extended cab, flareside, the short bed, and 4WD. Lightning models were 2WD short bed regular cab flareside 1997-2003 models with a tuned engine. Lightnings were also all built in Canada.
Next up is F-250, which is classified as a "heavy duty" truck by Ford. All Big Three manufacturers sell a heavy duty version of their regular truck, and all are available with six wheels. Ford's is built on a seperate platform that it shares with the huge Ford Excursion SUV.
No models F-250 or above ride on the same chassis as the F-150. Calling it an "F-series" is a little absurd in that regard, but they do anyway. Most heavy duty trucks (Dodge and Chevrolet also offer them) offer huge engines and several turbodiesels. I'll be honest when I say heavy duty trucks are not my part of the market and I know very little about them, but this is a basic F-250:
This is an F-250 Lariat. Really it's huge - most F-250s are not crew cabs but rather extended cabs; regular cabs do exist as well.
F-350s are the ones with six total wheels, but that isn't standard and as I said the six-wheeled ones are rare even in the states; it's pretty much only used for heavy-duty towing:
Standard F-350.
The only difference between an F-250 and an F-350 are payload capacity. This is reflected in the respective names - F-150s have a 1500lb payload capacity, F-250s have the 2500lb, etc. These things came out several years ago, and Ford has yet to give them a redesign. For 2005 they were "totally redesigned" according to Ford but all they did was strengthen the chassis (I think) and add some chrome (I know).
F-350 Dually. Needless to say, these things are legitimate.
It goes up from there, but F-450 and above see commercial applications only. Nearly all US ambulances are built by Ford, but I'd say more than half are actually E-series vans, which are similarly numbered. (E250, etc.) The rest are F-450s with the bed completely cut out. The vehicles are sold to ambulance-fitters with just a cab and a rear axle:
That's an old one (pre-97) but you get the idea.
Anyway, the ambulance-fitters put the box on the back and the medical supplies, paint it, and ship it.
That's pretty much the deal on the Ford F-series.