The backgrounds and numbers/letters are required on all three plates, and are as follows:

AA Blue backgrounds, white numbers
A Red backgrounds, white numbers and letters
B Yellow backgrounds, black numbers and letters
C Green backgrounds, white numbers and letters
Sportsman 60+
Minis 		White backgrounds, black numbers

Class
Letter Requirement
Division Levels
Semi-Pro
no letter
AA
251cc+ (Open)
P
A, B, C
250cc
X
A, B, C
200cc
A
A, B, C
Vet 30+
V
A, B, C
Senior 40+
S
A, B, C
Super Senior 50+
M
A, B, C
Masters 60+
L
no class
Womens
W
B, C
Youth
Y
C
Sportsman
no letter
no class, AMRA beginner