Not as famous as Shelby, but the same sort of business. It's interesting that both John Fitch and Don Yenko were World War 2 fighter pilots who became succesfull race drivers before going into the business of selling highly customized/modified new cars.
I'm running the risk of creating a theme for the vehicles I'd like in the garage. In the vein of Unobtainium let's talk about a running, driving prototype vehicle.
The Ford Ranger Lightning Bolt.
Take a regular cab flareside Ford Ranger, pluck out the 4 cylinder engine and replace it with the supercharged 5.4l V8 power plant out of a F150 Lightning. Swap the rear end, front suspension and box the frame so it doesn't get tied in a knot and you have a 1/4 mile devouring beast. I remember reading years ago the account of a journalist who got to drive the truck and pulled up to a red light next to a C5 Corvette. The Vette driver laughed at him and hit the gas, taking off as the light turned green. The journalist in turn put the Ranger's pedal to the floor and blew the doors off the Corvette.
Later Ford would introduce the Thunderbolt Appearance Package for the Ranger and thoroughly disappoint me (although I still secretly wanted one when I was in my mini-truck phase). The aftermarket company they partnered with, SLP, offered several levels of this package with the top level getting some performance upgrades. I think it pushed the 4.0l V6 at the time into the 230hp range...nowhere near the almost 400hp of the Lightning Bolt obviously.
Fairly sure @Dave was looking for Rare Rigs, meaning vehicles of the 4x4 variety so I'm going to get off my street vehicle trip and hope someone posts up something designed to get dirty in the middle of nowhere next...