Need scope mounts for Nylon 66

I thought is was like a 3/8ths dovetail "air rifle" mount?

In my opinion, I'd say, "Don't bother." I really like the Nylon 66. It was the first rifle I ever had. Mine is an "Apache Black" model, just like the one in the above pic. Nevertheless, it's the rare Nylon 66 that shoots well w/ a scope. The action of the Nylon is........plastic, not metal. What appears to be metal is actually just a thin piece of sheet metal that drapes the plastic receiver. The barrel is attached to the plastic receiver and is not very stable. The Nylon 66 accuracy is fine using open sights since the front and rear sights are mounted on the barrel. Consequently, when the barrel wobbles in relation to the receiver, accuracy is not effected. On the other hand, when on puts a scope on the 66, it's attached to the receiver. Now when the barrel wobbles in relation to the receiver, accuracy deteriorates. That's exactly what I experienced when I put a scope on my 66 some years ago. I was bound and determined to make it work, especially since a long time buddy had experienced the same problem w/ his Nylon; I really wanted to show him it could be done. I even researched the net looking for a remedy, but one doesn't exist. Enjoy your Nylon 66 for what it is: a light, sweet handling gun that's an open sights only proposition.

As has been said, the metal section with the mount rail is a cover on the receiver. It's held on with 2 bolts that go thru the metal, thru the plastic receiver and thread back into the cover on the other side.

So the cover does have some play in and SOME owners have had issues with scopes holding zero.