What designates an F-250, F-350 and F-150 apart from each other? gear ratio?

I wouldn't mind knowing so I can put some different badges on my truck if it suddenly becomes a "250" haha.

 

Well here is the wiki take on it.....based off year and GVWR

Sixth generation (1973–1979)Sixth generation
Production 1973–1979
The truck was redesigned in 1973; the grille for the 1973 model year featured two silver-metallic plastic inserts divided by an aluminum bar that was part of the main grille frame, with the letters "F O R D" spaced out in a thin rail in the upper part of the grille. Large round headlights were on either side of the grille with the park/turn signal lamps placed above in the same rail where the "FORD" lettering was. Medium-duty models, however, weren't redesigned as drastically as the light-duty trucks. In fact they were incredibly similar to the fifth-generation medium-duty F-Series trucks. In 1976, this familiar "split-grille" design was facelifted slightly to feature black accents around the headlights and a refined appearance overall. In 1978, the round headlight design was retained for the regular Ranger and Custom trim levels. The XLT and "Lariat" trim level incorporated rectangular headlights with optional chrome headlight doors and chrome grille insert. The split grille design was overhauled in favor of a single-piece grille insert design. The headlights were also placed in a more stylized "insert" themselves, and the park/turn signal lamps were now placed below the headlights. Additionally, a new chrome-plated "F O R D" letter set could now be seen on the hood immediately above the grille. A luxury Lariat trim was also introduced for 1978. In 1979, the round headlights were replaced by rectangular headlamps across all the trim levels and the surrounding grille insert that framed the headlamps was now available in either black, or chrome to match that of the aluminum grille frame.


The similarities between 1967 and 1972 medium-duty F-Series, compared to those made between 1973 and 1979.In 1973, a new model was offered, the F350 SRW (single rear wheel) pickup. These were a new heavy-duty pickup with contractors and camping enthusiasts in mind. The trucks rode on a longer-wheelbase chassis but were the same overall length as an F250 pickup. If you ordered the Camper Special package on an F350 SRW it became a Super Camper Special which was designed for the much heavier slide-in campers coming on the market at that time. Other changes included the 1974 introduction of the extended super cab version. The F-150 was introduced in 1975 to help circumvent coming emissions requirements. These came with a maximum payload of 2,275 lb (1,032 kg) when properly equipped. With the 1/2 ton F-100 still in production, the new F-150 was referred to as the "heavy half" ton by some people.

In 1976, the F-series became the best-selling truck in America, a position it has continued to hold since. This generation is noted for the durability of the body panels as Ford used extensive amounts of galvanized sheet metal to fight corrosion. 1977 was the first year for smaller cowl insignias moved near the windshield and the last year for the medium-duty F-500.

The GVWR ratings for these trucks was tied to a combination of wheel, spring, axle and brake combinations. The series code on the ID tag denotes which model and from that it can be determined what weight rating each vehicle has. 4×4 trucks can also be identified by the VIN number and on the ID plate as a serial number. For example, F10 is an F-100 2-wheel drive, but F11 is an F-100 4×4, and so on. Serial numbers beginning with an "X" are SuperCab models.

Starting in 1978, Ford redesigned their Ford Bronco and based it upon the F-150. The Bronco was now virtually identical to the F-150, except for the unibody design structure. The new Bronco incorporated design characteristics which eliminated leaky roofs and body flex associated with other full size removable top utility vehicles of the era. This allowed Ford to compete better with the Chevrolet Blazer by offering a larger and more luxurious SUV while minimalizing production costs since many (especially the most complex and expensive) parts were shared with the F-series trucks. The Bronco was only offered with the 351M and 400 V8 engines

Models:

F100 F101 F102 F103 F104 F105 F106 F107 F108 F109 F10N: 1/2 ton (4,550–5,700 GVWR max)
F110 F111 F112 F113 : 1/2 ton (4×4)(5,250–6,500 GVWR max)
F150 F151 : "heavy" 1/2 ton (6,050–6,200 GVWR max)
F140 F141 F142 F143: "heavy" 1/2 ton (4x4)(6,050–6,500 GVWR max)
F250 F251 F252 F253 F254 F255 F256 F257 F258 F259: 3/4 ton (6,200–8,100 GVWR max)
F260 F261 F262 F263 F264 F265 F266: 3/4 ton (4×4) (6,500–8,400 GVWR max)
F350 F350 F351 F352 F353 F354 F355 F356 F357 F358 F359 F35P: 1 ton (6,000–10,000 GVWR max)
F-360: 1 ton (4×4) (8,550 GVWR max)

 

VIN, ID plate, suspension and drivetrain combinations.

 

Frame and associated bracket thicknesses as well.