Too fast for us... Eleven minutes between question and answer.<img src="images/smiley_icons/icon_smile.gif" border=0 alt="Smile">
The Sun System Handbook will have a link for each system that describes the System Specifications.
Every Sun system that has native PCI slots is compliant with the 2.1 spec.
I just glanced through a few of the SSH pages and seem to remember that the Ultra-30 was the first PCI-based system to ship to customers, in May 1997.
Here is the U-30 page in the SSH
<a href="http://sunsolve.sun.com/handbook_pub/Systems/U30/U30.html" target="_blank">http://sunsolve.sun.com/handbook_pub/Systems/U30/U30.html< ;/a>
Since the 2.1 spec was included in that system design, then the board designs of everything newer would likely comply -- no sense to go backward.
The only son-of-a-gun PCI-slot item that I have doubts about would be the oldest PCI I/O boards for the Enterprise systems [ E3000 -- E6500 ], but those boards probably comply with the spec as well.
Does anyone remember when that specification was published?