I'm going to say they are late '66 to early '67 and that the arm with four taps for the set screws would be the correct one.

Two holes is probably Fullerton era, as they realized by then that it was cheaper to just tap it twice and tough luck if you broke one off. Normally, two was all it took to hold it. I suspect their engineer (Thompson) thought it a good thing for heavy handed drummer to have some extra holes. :D

Let's see what the others have to say.

Nice set. Yes, I believe Dan is right about the two hole being the later Fullerton.

I've always been under the impression that the 4 holes in the tom arm were there to give you the option of where you wanted to place the set screws. It would make no sense to have set screws where you couldn't easily access it with a drum key, and easy access would depend on how you have your tom situated. I've also been told to never use more than two set screws and that that was the intention when designed. If you use more than two screws you'd have the screws fighting each other, and in turn you would need to tighten the screws more,and that will wear on the ball out much faster.

This has worked for me since I fell in love with Rogers drums of that era.

My Fullerton short arms only have two screw holes, so you'll want to keep just your 4-holed Dayton arm. Let us know if you're posting the Fullerton arm in the For Sale section. Also, your cymbal collet appears to have a Fullerton cast nose on it. You'll want to replace that with a machined one.

Mike

There were indeed 4 holes to allow easy drum key access of 2 screws. The 2 screws would push the ball against the opposite side of the housing to give a large friction surface to hold the arm in place.

If you used all 4 holes with screws, the small surface area of the screw heads would mean needing to over tighten them to hold the arm in place. This tended to tear up the ball.

Making that pearl thingy go away could be done with a chrome plate in place of it. Not much you can do with the holes, but worse things have been fixed and made almost invisible.

Thanks for all the input! I actually have an old Cleveland kick drum shell the is pretty much destroyed but will be a perfect donor to drill some nice dowels to fill those holes as legitimately as possible.

One last question!

This would be a glitter glass silver and not a regular Silver Sparkle wrap correct?