Did some more playing around on Amazon and Ace Hardware today. I found 2 alternative YakAttack rails (on Amazon) that fit the 67D series 20 balls with no issue. The silver one shown GT175 is metal which is awesome, but obviously too long (and too silver), I just ordered to see if it fit as it was the fastest available option on Amazon. It's available in other sizes and in black. The Black one shown GTSL90 is fine as-is, but it's plastic and labeled "light duty". Not 100% sold on either just style-wise, I just wanted to confirm they do indeed work as an alternative option:
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@greynolds , I did also source the longer bolt from Ace today. The 67D supplied bolt was M6 25mm. I bought a couple M6 30mm and they are just the tiniest bit too long. You can see the threads stick out just a smidge on the bottom when tightened down. I'm sure this would still work, but I'd either have to accept the rail may not sit 100% flat, or at the very least it'd scratch my Gamiviti metal. I considered putting a layer of felt or rubber under the YakAttack, but I already have my hardware that attaches the rail to the metal lengths dialed in, and don't feel like doing that all over again. Now Ace only had 25mm and 30mm long, nothing in between. 27-28mm long would probably be perfect, but I'd have to find that odd size online somewhere. I also am considering filing a mm off the end, but always a gamble whether the nut would thread after. I'll probably try that no loss besides a couple $ in bolts.
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The more I look at them I really like the silver metal version. I may stick with that and just find a shorter black version of it. Just as low profile, but metal and same width and possibly same hole spacing