How do I know if my 99 blazer is equipped with a keyless entry receiver?

On the glove box door, look for the (RPO) options code.

AU0 :Lock Control, Remote Entry -Keyless Entry Domestic
or;
AX3 :Lock Control Keyless Entry System


http://www.automotiveforums.com/t450285-__list_of_rpo_codes__.html