1968 Dart GTS 340

Quite right.

And to answer someone else's question, the "M" engine designation meant "special order V8", which usually means a 440 in an A body. For a 69 1/2 B body (which was never referred to as a 69 1/2 by the factory) meant a 440+6.

An "M" engine designation "always" means 440 in an 69 A-body.

Grant