> (SID & 0xff000000) | ((SYS_TYPE >> 8) & 0xff0000) | (SYS_TYPE & 0xffff)

The only architected bits are the top byte of the SID and the top byte of
SYS_TYPE. The SYS_DEP field in SYS_TYPE (byte 1) also seems to matter in many
cases. However, the bottom byte potentially varies according to the box you are
on. For example, I have at one stage come across a VAX 4000-300 with a SYS_TYPE
of 0x01340402: bytes 3 & 1 match those you report but bytes 2 and 0 do not
match (my guess here is the the 0x49 in your case is a console FW version; I'm
not sure what the 0x01 vs 0x02 field is - maybe VAXserver vs VAX?)

Antonio