Chassis Number? Where?

I am looking to purchase new front and rear brakes rotors & pads for my 2000 ML 430 and in the fast lane its asking for which chassis number. Can someone tell me where I should find the chassis number, beyond the W163? They are asking to pick one of these numbers? I check my VIN # thinking that would be the tie in but, my VIN is xxxxxxxxxxA194329

-A-145272
-X-707755
A-145273-
X-707756-





Looking to do the brakes myself after my dealer gave me a price between $1200 to $1500

Thanks for the help!