The numbers differentiate between colors... the 3AC is the Red/White/Blue Tri-Color. As far as the other two go, I'm not sure which is for the Black bike, and the Red/Silver. You can look at the painted body cowls in the parts listings, which will have the Honda Color Code in the description for the part. Your bike has a Color Code sticker, which I think is located in the storage compartment under the pillion seat.All the parts websites I'm finding list 3 different models of both the CBR250R and CBR250RA designated by either AC, 2AC, or 3AC following the main model number. Then they list identical VIN#s. What's the difference?