Just came across this while going through piles of cards, merging another collection with mine. Found some other things that were formerly not listed in the slot guide that I'll try to post as well.

If you look at the 9th issue silver Jack's Club card from Horseshoe Casino in Bossier, LA there are actually two versions of that card.

The original 9th issue card has a metallic silver front and the paragraph of text on the reverse is 17mm top to bottom.

The card I'm adding as the 10th issue Jack's Club has a plain grey front and the reverse paragraph of text is now 18mm top to bottom.

Very distinct difference when holding the two cards side by side.