Well this is digging up an old post.
I don't own a Boss unfortunately, but just looking at images of Boss engines, I see the wide band on the dual vacuum distributor.
I "borrowed" this pic off the net. Apart from the correct K625J engine sticker and the rev limiter, I have to assume it's a real Boss 351.
As you are replying to my post in a 2 year old ad, I assume you didn't sell it for 3K.
I know my 71 Feb built Mach 1 did have the wide band distributor until I foolishly let it go as a core replacement for a reman with a narrow band dual vac.
As I'm NOT the expert on this subject, the only main difference I know of is the dual breaker plate with actual bearings, not the cheaper nylon bushing on the other 351C distributors.
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