The latest snapshot is located on:

ftp://ftp.netbsd.org/pub/NetBSD/arch/mac68k/latest/

Does the 550 have an '030 or an '040 processor?  If it's the latter, it
definitely won't work under 1.2 (no SCSI support ;-)

Hope this helps.

Later.

-- 
Colin Wood                                      ender@is.rice.edu
Consultant                                        Rice University
Information Technology Services                       Houston, TX