Yep, there are a lot of parts that go into building a car. When I built my first hotrod (1915 Ford C-Cab replica) many years ago, I bought a beat-up '64 Chevy 4-door for $75, drove it home, and stripped it for parts. I used the engine, trans, rear end, drive shaft (after I shortened it), alternator, voltage regulator, horn relay, gas tank, master cylinder, brake pedal, light switch, ignition switch, wiper switch, fuse box, and radio. I rebuilt the engine (327) with fresh rings & bearings, but used all the other parts "as-is". I traded the radiator even-up for a smaller one. I figure it saved me a ton of money by using a donor car for all the major components...