I just got a Rat with pots marked '97 with a relatively low serial, made in USA, mojo LM308N chip, etc... I seriously don't know why I resisted this pedal for so long! There's just something about it. It can be grungy and bright or fat and crunchy; any way I tune it, I just can't get over how the gain just seems to bloom beneath power chords.
I did mod mine by upgrading components & adding clipping options, but I left the values the same- I keep going back to the Vintage/stock settings anyway.
I have compared many Rats together and built/modded/fixed a bunch also. I would say as a general rule of thumb that the WF Rat reissue seems to have a touch more midrange than the 90's Rat reissues, whether they are the small box or the large box. This would make the big box Rats in comparison seem slightly fatter or tighter in the bass. But we're talking not much here. Live into a 4x12 or with the bass up on your favourite amp, Rats just destroy. So good.
The Big box in the pics there is a Vintage Rat, as in the model that we called a Vintage Rat. BTW the first generation of those came out when the original big box was less than ten years old (1991), so we're well into "vintage Vintage Rat" territory here haha.
I'm guessing by the PCB it is a second gen. Great pedal- I have one too, approximately the same year IIRC. It has the LM308, the large format pots, and was made in Kalamazoo. Get it and enjoy!
As for the sound of the pedal, my own Vintage Rat is darker and woolier than the WFRAT, but from my experience testing Rats I would say that that isn't necessarily a characteristic of the VRAT models, just an inevitable variance due to component tolerances in an analog pedal.
I've had a Rat for several months that I purchased from Modest Mike's Mods.
Then today I just received the Skinner Box from Stomp Under Foot.
If the new one is like a real vintage Rat, and it should be because of the parts used, then a Rat is a great pedal for distortion and clarity.
If it's not, then the Skinner Box is a fantastic pedal and you should check them out.