Dating fender guitar pots
Ibanez reissued the narrow TS-808 as the "35th Anniversary TS-808" in 2014.It is a very accurate reissue except they used JRC4558D chips instead of the 1458 chips.SRV used the TS-808 for his trademark juicy strat tone.
(R) means the trademark after Ibanez on the top of the pedal.
The most popular was the TS-9 tube screamer, which is almost the same as the TS-808 internally.
Externally the on/off switch grew to fill about 1/3 of the effect.
The TS-808 and its generation have small square metal on/off touch-buttons. There were some TS-808s made in the 1979 period, mostly for other than USA markets, that came in a narrower box.
These have a bottom plate that unscrews to change the battery like an MXR pedal, no plastic battery cover. It uses two 1458 chips which are the 1st version of the low-tech dual op-amp.
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The Malaysian RC4558P chip was probably used to save some money as they were cheaper than a Japanese made JRC chip.