Thanks for the tips and info on the boom end parts. My boom lives outside my back door instead of on the boat, so after reading the posts here I had a look at it.

To me the 338 boom is more EGG shaped in cross section than the Kenyon diagram, which is eliptical. The pointy end of the egg being the groove on the upside. And the boom OD measures 3.5" X 2.375". 3 1/2 X 2 3/8.

Is this just me being too picky again or is my boom an after market item? The castings at either end look pretty good, but given that old cast aluminum wants to crystalize, I think replacing them and having them for backups is the way to go.

Does anybody elso have a boom like 338's?
I would also like to replace the boom attachment on the mast track. While it looks good, it doesn't seem as robust as the boom fitting and it is held on by corroded fastenings thru thr track. Grateful for any comments.