Quoted from Jmckune:There’s a Funhouse with a Diamond plate playfield inside a WPC version (so wasn’t originally a diamond plate in the cabinet)
Not sure I understand this. Funhouse is one of the first WPC games. Also, there were many Funhouse diamond plate playfields installed, but not all.
From ipbd...
Reportedly, about 200 of the first playfields made were manufactured with "Diamond Plate" covering. Additionally, several years later and due to dwindling replacement stock, a set of NOS replacement playfields was manufactured which also had the Diamond Plate covering, although these are also reported to suffer from having the red color 'bleed' around the center playfield clock.