On Nov 7, 2012, at 9:35 AM, Cindy Croxton Electronics
Plus wrote:
  I am going to show my ignorance here, but would a
M0437 be of any use?
 I have 2 of them... See here for pic and description
 
http://www.welovemacs.com/m0437.html 
 Not for an SE/30, alas.  Those are essentially AUI transceivers using
 Apple's AAUI connector (a small-form-factor version of AUI pretty much
 only found on Macs).  They're handy for earlier Macs with built- in
 Ethernet but no 10BaseT connector, like Quadras and early Power Macs.
 Plenty of folks on this list may find them useful, though (but they're
 not especially uncommon). 
Farallon also made some daisy-chainable AAUI transceivers under their
EtherWave line but the ever decreasing price of 10Base-T hubs doomed them.