Brendanm,
I've got a set of fiberglass on the rear of my 46, from Jim Carter's. If you didn't know it, look beneath them, or give them a good thump, you wouldn't be able to tell they were glass.
In my opinion, they are of very good quality, and visually you'd never notice a difference between them and the original steel on the front.
I think you're gonna have an awful hard time trying to find NOS or as you said; "used ones that are worth a darn". IF and when you find them (for a 46), you're gonna be paying MUCHO DINERO!
