I believe the bios version is NTSC-4-1.00a
I dont know if this is any rarer than a normal one but i think my saturn might be one of those Model 1 Saturns with a Model 2 back because it has a notched power cord.
It's probably just another Saturn but lol.
its power cord looks just like my Dreamcast's power cord and it is a model one Saturn because it has the drive access light.
I ask this because Wiki says:
Identical to the Grey Japanese Saturn except for color: the U.S. model is black. A few have been found with the backend molding of the MK-80000A and the notched power cord using the 1.00a BIOS version.