I'm digging through a ginormous box of French stuff right now, and am having trouble differentiating the various models of Simplex derailleurs. I know the Prestige are the plastic ones, and have a vague idea that 'SJ' denotes an alloy RD...but beyond that I'm hopeless. Some have model numbers, and some don't. I'm still learning the ins and outs of French stuff...is there a handy reference guide anywhere, or someone who'd like to lay out a few rules of thumb?

Thanks.