I'm not sure of the interchange for all of the models, but there are currently several listed on Ebay. 4006, 404x, should fit. Maybe the full size double stack 9mm as well.
Someone here should be able to tell you exactly what will work.
Oh the part # for the 411 Sideplate is 106770000. A call to CS at the mothership is always the first step. They still do stock some of the more common parts, so might be able to help you out. They'd also likely know the interchange.