The first run of Stevens were staggerfeed with the round rear action. They started slowly swapping over to centerfeed after they had already done it with all of the Savage line. For a couple years afterwards(and once in a while still) you could have still found a staggerfeed model on the shelf of the small gunshops that dont move guns as much. Just new-old stock.

All of the Savage and Stevens line is now being produced in centerfeed though.

If your magbox is attached to the action it is definately a staggerfeed. Your action screw spacing should also be 4.275".