This question is one which really interests me. I've found a supplier for the 3353 here in Canada (since the 3373 is apparently not available, and the only difference I can find is that the 3373 is black); however, I am having a really hard time pinning down what adapters are needed to connect it to a standard mic bar.
In the archives, it notes that to get to something standard, you'd need part #3102 and #3366. #3366 has been re-coded as 'MIBA' (or BOMIBA). #3102 is 5/8" stud > 3/8" male thread adapter, and #3366/MIBA is a 3/8" F adapter to 5/8" Male.
Now... the supplier I have, is suggesting that this isn't what I need, and what I really need is 'SPA18' (1/4" > 5/8" directly - see link below).
So... I'm a little confused on what one really needs, and don't wnat to order something that won't help. :-)
The adapter they've recommended is :
http://www.manfrotto.com/product/templates/itemalone.php3?itemid=178edit: OK, I'm an idiot. The above link is for the specifications for the 3353 mount, which seems to be a 1/4" mount, rather than a 5/8" stud. So, the only adapter one needs on the 3353 is #3103 (1/4 F > 3/8 thread) ... perhaps? (
http://www.manfrotto.com/product/templates/itemalone.php3?itemid=158)
I'll wait for an 'expert' to chime in...