need brakes but not sure which system I have.

[not4spd]

so I need brakes and have a problem. I'm not sure if I have the heavy duty brake system or not. Since the RPO sticker is missing is there a way to still tell?

 

[vetteoz]

J55 (HD option )fr rotors are over 1" thick (28mm) 13" OD
JL9 (std ) fr rotors are about 3/4" thick (20.5) 12" OD.
No difference in rears

 

[not4spd]

that is much apprechiated, time to bust out the tape measure.