I just received an NOS Slingerland 'Magnum' pedal I bought on ebay. I've developed a bad habit of restoring old hardware. Serious illness!
ANYWAY... for whatever Slingerland did right or wrong in other areas of the business - and I don't know much about them (except that my first set was a mix n' match used Mardi Gras kit). But their hardware ideas and production are absolutely first class.
Well thought out, impeccably manufactured, and not susceptible to bean-counter hardware short cuts.
YOU probably already know this -- but I think when I have something positive to say, I should say it. Kudos to the Slingerland Company! At least of that era!