Dodge had a few sub models of the Charger. I’m not sure of a “Sport” model Charger. There was a “Midnight Special” Charger.
When the Magnum was brought to the table in ‘77 for the ‘78 model year, the story goes like, the executives were shown the drawings for the new & restyled Charger. The “New and radical” design made the executive board nervous and they didn’t want to hurt the Charger name and image anymore. The designers were insistent as much as the executives were so a compromise was made by calling the new Charger a Magnum and they kept the Charger for ‘78. Selling somewhere around 1500 or less Chargers vs the 55,000 or so Magnums, the Cordoba style Charger was canned. There is no such thing as a ‘79 B body Charger.
The 2 year Magnum run was comprised of the Magnum XE and a GT. (GT with and without T tops) It was also called an X body. When you go to look up parts at a dealer, (& if you can find an old guy...) they will open up the books to the X body section. There you will find Magnum parts.
Being that all the B body cars from ‘75 & on are based on the Cordoba body core, anything can be redone with the proper parts for that car which would mostly be, hood, fender, door, trunk lid, grill and the parts that surround them like the lights, signals and sometimes bumpers for certain models. An example on the Magnum parts sharing would be like the bumpers are shared with the 300 but not the Cordoba. Deck lids are another. Fenders work fine but some say the doors are different. I haven’t take a good look there to make that call. Rear deck lids are the same as well. But not the rear tail lights or everything on the nose of the Magnum.
Mechanically speaking, there all the same. Electrical is all the same. Minus partial or full gauge panels. All the wiring is there (or should be) for A/C and P/W hook ups.
Cosmetics on the inside will swap but the styling is different as different gets. Car to car, year to year.
I don’t remember a funny car version of these cars being sold or professionally used. While it would be a lot of work, it’s nothing that time, talent and bags of money couldn’t fix.
I just don’t remember a bunch of variations to these cars. Unlike a Duster with a bunch of different sub model names. Duster, Duster 340, Duster light, Space Duster, Good Duster, etc....