Hello Djustham,
First I'll say what a great looking Mach1 you have.
It would be a check in the plus column if you did have a Boss engine. Depending on how long ago the original engine was replaced , it could certainly be possible. Before these engines elevated to cult status, it was much easier to find Boss engines and parts in a salvage yard. I remember in early '81 I was approached by a person looking for some Boss 351 rods, pistons, and damper. He had been looking for an engine for a project and this one fell into his lap from a salvage yard.There had been zero interest in this engine from anyone looking for a "Regular" 4bl 351. Guess the solid lifter noise and adjusting valves scared off the tire kickers. I personally like the sound of solid lifter Ford engines. I grew up to the sound of solid lifter 427, 271/289's, and Boss engines, pure music! Oh, and the project, he was mounting a 55 Chevy body on 4x4 F150 frame!
You have already received a lot of really good ID info. The Mustang Tek site, while not always 100% correct, is a good source for ID info. There was a replacement for the earlier mentioned damper. The original is part# D1ZZ-6316-B (ID# D1ZX-AA) . There was another that was the production installed damper for the '72 351 HO and the service replacement for the '71 engine. Ford part# D2ZZ6316-A (ID# D2ZX-AA). So running changes and service replacement parts can also add to the fun of trying to ID certain parts.
Just as a reminder, any number you see on a part is always going to be an engineering and not a part number. Ford NEVER cast, molded, stamped or printed the actual part number on any part. As SVO2SCJ posted, there is a lot that can be investigated without going into the engine. There are many of us that have had experience with these engines in one form or another. So if you need ID help or just have questions, don't ever hesitate to ask. That's why we are all here! :classic_smile: