Unmarked clasp. End piece 306. And there is a stamp 3-73 on the clasp. Any idea what is it?

 

How about a shot of the top side so we can see the links and full taper...

 

I don't have the watch in my possession (away at the spa) but I think this is right for 166.171 and similar - square/cushion seamaster from early 70s.

Comme ci:

 

This bracelet came with a 145.014 (turned out to be 145.034) Mark II. The watch and dial itself is another mystery.

Super Weird Speedmaster Mark II Dial
https://omegaforums.net/index.php?threads/Super-Weird-Speedmaster-Mark-II-Dial.53151/