You might also mix parts to make a different version of a car. I've used the smaller engine out of a '67 GTO to simulate a small block for a "downgrade", making a 70 Buick GSX into a 72 Skylark Custom, and parts from various kits and some scratchbuilding to make a 71 Charger R/T into a base model. I've also got a 440 Six Pack from a Superbird, and I'm going to redo the intake for a 4 barrel carb and make it a 383 for my 68 Road Runner. I've also swapped things around for accuracy's sake, like using the engine/transmission out of the 87 Monte Carlo SS as a replacement for the piece of junk in the Trumpeter 1978 Monte Carlo.