Calling Boxster Experts
 

So I have a new to me 1999 Boxster. The seller did tell me the engine had been rebuilt. So today I was changing the plugs and noticed the head has the number
996 104 227 3r on it. Did 5 minutes of research to discover this is a 911 head. Is that right? What do you experts purport was done during rebuild. I purchased new plug tubes to replace with the plugs and of course this head doesn't use plugs. Demystify this for me.

You mean it doesn't use plug tubes? The later boxsters didn't use plug tubes either (mine is an 03 Boxster S) so it could have been a rebuild with newer engine parts. Can you get anymore info from the seller?

Correct...from what I can tell it doesn't use plug tubes. So I assumed it would have been rebuilt with newer engine parts. Does that number I provided mean anything?

That PN is not for the head - its for the "head cover lid".

The Boxster PN's for this part are 996-based (for example, 996 104 637 5R is the part for a 2003-2004 2.7L base engine). Often 986 and 996 parts will be interchangeable between years and models.

I purport that during the rebuild someone bought a head cover lid from eBay since they are probably interchangeable and used it on your 986 engine. You'd have to actually check the head PN to know where that came from.

At this point, nothing to worry about, nothing to brag about.

or perhaps it was not rebuilt but swapped with a later boxster engine, is the other side also non-spark plug tube?