71-71 Chargers are an entirely different car than a 73-74.
73-74 was re-engineered to have less NVH, and has a huge rubber isolated K frame with different rad support, aprons, frame rails, longer torsion bars, an isolated torsion bar anchor crossmember behind the transmission crossmember, a rubber isolated steering column, rubber isolated rear axle
Yes the hoods and trunklids will interchange, but that's it for bolt on body parts.
The fenders and doors from 71-72 will not fit. Fenders have a totally different inner structure due to the totally different inner aprons, rad support of the 73-74 and also the wheel wells were raised up.
Body lines of the doors are completely different to match up with the totally different quarter panels and weigh a ton with the side impact beam inside.
Hoods will physically fit but do have year to year variations listed in previous posts. The trunklids fit, but 73-74 use the large key cylinder with the huge nut retaining it, where the 71-72 trunklids use the smaller clip in cylinder.
Starting in 1973, every engine family uses a different K frame and spool mounts. Big block will not bolt onto a small block K frame
73-74 Charger may resemble a 71-72 from a distance, but they are a completely different car underneath, and are actually closer to a Córdoba structurally.
Put a 71 Charger and a 73 Charger on a hoist and they will look completely different underneath.
Put a 73 Charger and a 79 Córdoba on a hoist, and they will look almost identical.
The 75-79 Córdoba, and all other 75-79 B bodies including the 79-81 4 door St Regis, Newport, Gran Fury, New Yorkers are essentially the same car underneath as your 73 Charger and more interchangeable than a 71-72 Charger is.
