b block size, no tag or stampings I can find

Someone's attempt at a very short-dwell dual-spark distributor?

Or some Ford/Autolite distributor?
http://www.mre-books.com/sa69/sa69_8.html

Doesn't look like a car distributor, maybe a marine unit?

Throw it back in the box you found it in, about as desirable as herpes.

That funny right there

the lower shaft is 3&1/2"? (B size). the condensor looks new(er) & the points likely are. check how much side to side play the top shaft has (point tension wears the bushings way faster than electronic ones do). It'd be worth something to someone.

someone emailed me and said it's a Mr Gasket Street Spark missing it's tag.

Looks like an old Mallory.. YL? I think. been many years since I had one.

Those are a little different, not a great photo, I'll need to compare them both next time I'm at the shop