Gord, your model 3 was tapped for a Weaver T mount, they don't make them anymore but you can find them on Ebay.

The one hole is for a model 3S peep, if I get time in the morning I'll take a pic of the one on my model 7S so you'll know what to look for.

I have one on mine and I was sighting it in on Friday and the **** gun went full auto on me, gotta figure out what went wrong yet.