I saw the same effect on my 3/60 when switching from 1.2 to 1.3, and
it created a bit of headache to me...Moreover, my two CD-ROMs at
IDs 3 and 6 swapped their names...

It seems that while 1.2 followed the SunOS style of assigning names to
IDs, 1.3 switched to a more dynamic approach like e.g. Linux does: scan
the IDs from 0 to 6, and assign names sxx, cdx, and stx in that order.
It would be an interesting question what now happens to an old "shoebox"
with 2 ESDI drives on LUN 0 and 1.  I think such constructions were
the reason why SunOS incremented by 2 for every ID...

Alfred Arnold