Complex sentence: The 400 was only ever produced with a 2-barrel carburetor, except for 71 year models which came with a factory 4v all had cast-iron intake manifold, and the smaller port 2V cylinder heads.
Split into simpler sentences: The 400 was only ever produced with a 2-barrel carburetor, except for the 1971 model year which came with a factory 4-barrel. All had a cast-iron intake manifold, and the smaller port 2V cylinder heads.