Found there are two variations of the 1st issue black Winners Circle Players Club card, the one that has the golden horseshoe on the front from Horseshoe Casino in Hammond, IN.

On one variation the reverse text is 72mm wide and these cards all seem to have an 11mm wide magnetic stripe.

On the second variation the reverse text is 70mm wide and these cards all seem to have a 12.5mm wide magnetic stripe.

I'll get scans on the ChipGuide when we get to the Indiana cards.