Go with the chassis number both gull arm and fireblade start with MC22- but the fireblade go on as MC2211XXXXX and the Gullarm as MC2210XXXXXX thats the best way to identify the two. There were few more from back in the day when i used to own and ride a gull arm that i remember. To start off with the RPM redline on the fireblade is less (18,000) than the gull arm which was (19,000), I also vaguely remember the fireblade had running lights and gull arm you had the option to turn it on and off.