The switch to the “Small Box” RAT was essentially just a cosmetic makeover. While the circuit remained the same, the enclosure evolved into a more compact version, with a 12-gauge U-shaped base. The Pro Co logo sat next to the RAT logo on the pedal top, silk-screened in black inside of a white box. In 1986, the logo was reversed to white on the black, painted metal.
text from Pro Co website
02/25/2017: ToneHome is looking for an Ibanez CS-505 narrow box first issue with flying fingers side graphic. Any hint is highly appreciated. Other than that we're looking for boxed effects or just boxes for Ibanez narrow box GE-601, AD-80, CP-835, OD-850. Please submit your offers or leads here: e-mail