I couldn't find anything that looked like a driver for this, but 
as an act of sheer optimism I plugged a Sun quad ethernet into hobbit
an (ss2).  

During probing I got...

le0 at sbus0 slot 0 offset 0xc00000 pri 5: hardware address 08:00:20:10:1d:55
qec at sbus0 slot 1 offset 0x20000 not configured
bf at sbus0 slot 2 offset 0x0 not configured
cgsix0 at sbus0 slot 3 offset 0x0: SUNW,501-1672, 1152 x 900, rev 6

qec is the quad ethernet card
The card in slot 2 is actually an fddi adapter...

Don't suppose anyone has driver for the ethernet card?

--sjg