Before the current version of the Overarm Pin Router (which clamps to the way tubes), there were a couple of stand alone Overarm Pin Routers marketed by Shopsmith.
Does anyone know the diameter of the tube that the the old-style OPR clamped on to? There's one near me and I'm wondering if it could be adapted to attach to the way tubes like the current version.
If you want to explore the manual showed pictures of the arm mounted to a drill press. Don't know if an original tube or a drill press of the correct size would be the easiest to find.
BTW they warn against trying to shim to get it to fit.