Kevin, I have an "A" type plate with my 1617. This uses 4 screws in slots and works very well. The screw holes are hidden under the sub base plate on the fixed base. Oak Park changed the design so either base could be mounted to the plate. A solution is to get a flat washer and use a large center punch to cup it. This washer will increase the effective diameter of the screw head so it will not pull through.
"Living in the D" (this means Detroit!)
"It's fine to disagree with other members as long as you respect their opinions"