GTS Motor info

A lot of misnomers on 67-68 bigblock A bodies. Not all 383s had an H stamped on the pad below the dizzy especially early blocks. Majority of the blocks with the H stamping that I've found were in 68-70 Road Runners. The block in my GTS didn't have a stamping. It was an early June 67 casting. As far as the bosses go, they are not inherent to the bigblock A body. 65 C bodies had bosses for the driver side motor mount which is similar to the Big Block A body. Some blocks had bosses not drilled. There were 71 castings that had the bosses drilled. I had a 71 Charger SE with drilled out bosses

Same holds true for the horsepower ratings. Mopar folklore contributed the 5ph difference between the Roadrunner 383 magnum driver side manifold and the bigblock A body driver side exhaust manifold. The actual HP difference was due to the camshaft profile. The Magnum 383 had a slightly hotter cam. Several years ago we did some flow testing with the various HP manifolds, C body, B Body and A body. The difference between the manifolds were negligible.

Bottom line is to go by the numbers.

Never say never about Mopars.