Yeah, the classic takes a straight pin ( like a dowel) no screw on it. It drops into the top of the rail before you put the body on ( no screw hole on the side). If the pin you have fits the rail you have, use the rt sear.
you can buy axle pins at agd
If you cannot use the classic sear with that frame due to the type of pin, I just happen to need a classic sear
let me know if you want to get rid of it.