Willie-O,I had a look at the Shure company's web site for the Shure Superpro PE50SP. Lots of other "PE" models, but no 50's. This is the link:
Link to Shure's discontinued mic site
At their home site, there's lots of good information about specific mics, and much advice about mic techniques for different situations.
Link to Shure mics /a>

You could try sending an inquiry:
Link to Shure's contact support group