The Accustock has an aluminum rail molded inside the stock that the action beds into.
The easiest way to tell at a glance is to look up inside the empty magazine well. You will see the aluminum rail inside the stock, between the bottom metal and the receiver.
Current production Accustocks will also be Accufit, with Comb and LOP adjustment, but older Accustocks may not have these features.
If you have any further questions or are unsure, please contact the Service Dept with your serial number for confirmation.