[Klutch]

Makes you wonder that they would offer a 351 4bbl with a 3 speed

My '70 Mach 1 also came from the factory with a 3-speed manual. It's rare, but as 22GT said, that was the standard trans even for a Mach 1. The auto and 4-speed were options and most buyers selected one of those options. But if you didn't check those blocks, you got a 3-speed manual.