Im looking for several parts for the bike like new gas tank and rear seat backrest. But I see several listed for this year. How can I tell if I have or need a K1/K2/K3/K4 or T/V/W/X/Y ? I dont know if this helps but its Yellow in color and a yellow tank is listed as T and T E33. Also as Y and Y E33. The part Im looking for the most is the backrest. If anyone knows please post. PS... what is the E33 for anyways ?