Lets not be too quick to label. It may be rare if it's an original 74 RR with the 318 4 barrel with duel exhaust and a 4 speed. We have one, all correct numbers sitting outside of the shop. They only built a handfull of these cars.
Ya, no 4 barrel till later years as I had an `87 Gran Fury cop car with the 318-4. Production number is low but I`d much rather have a 340 or 400 4 spd and I`d pay more for it than the lowly 318 car.