Here we have a classic ProCo Rat 2 with a 3 way Keeley mod, for 3 different settings of distortion.

From the Keeley manual:

Position 1: Stock "This is the classic Rat sound where you benefit from the increase in bass response due to the capacitor changes we make. The volume will seem low compared to the other modes, but this is the stock Rat output level

Position 2: Single diode asymmetrical: "This is the Mighty Mouse mode. Prepare for super volume output. We take out a diode from the circuit, so this thing is raging with volume. Great natural sounding gain and then some.... There’s enough volume to boost any amp into true overdrive"

Position 3: 3-diode asymmetrical: "This is the Phat Rat mode. Normally the Rat has two diodes in the circuit for clipping, but we add another in order to achieve a tube type tone. The volume is increased slightly and there is an added richness to the signal. Fatter and more complex characteristics are present in this mode."

Other upgrades include the Classic and favorable LM308 "Metal Can" OP Amp, and a "Boss Style" modern 9V Jack.

The LED is also blue, which I'm assuming was also part of the Keeley mod.

The battery compartment screw has been updated, as the aftermarket one that was in it was not a perfect fit. Now it's nice and snug.

The pedal case received a through cleaning, as well as the pots, and sounded great upon testing. Nice and "Ratsy!"

Speaking of the pots, it took a while to hunt down the year, but after lots of research, it looks like it was built in 2001, or at least the pots were, as the code on them is ER3977 0127. The number seems to correspond to the "01" as the year and the "27" as the 27th week of...

The pedal casing has a little normal wear and tear for a pedal as such, in this vintage, but still looks pretty snazzy after a lil' cleanup.

Not much else to say really, 'cept it rips! Get on it and blast!