I got to play 3 of the test machines back in the day at some of the locations. Dennis's, Galaxy Games, and Galaxy World were the three places I played them at. I definitely played the one with the alternate backglass in the old Bally cabinet. I believe there was a third version which was the alternate backglass in a Williams cabinet. The old Bally versions weren't on test long before they replaced them with the production model. Proto games had the regular flippers and production changed to the lightning ones.