Real glass backglasses on a few WPC games
Most WPC games use a plastic translight. No Good Gofers and Champion Pub have artwork screened directly on tempered glass, and Cirqus Voltaire has a screened acrylic backglass covering the whole backbox with speaker slots at the lower corners.
Systems
Games
Related tips
Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part One, Clay Harrell (pinrepair.com)