Yes, there are many versions - blackberry etc. and now a double Hotcake
with a master volume control, BUT as far as my experience with them is concerned, there are basically two types (incidentally that 77 reissue on the Japanese site is not even remotely similar to his original design - if it ever was original??)
The very early 77 units used a 741 type opamp (no, I don't remember who it was made by!) and a switch between the two extreme positions shown on analogguru's drawing instead of the later presence control. It also had a two stage high frequency rolloff - 10k and 12n, similar to the rolloff on the BSIABII or STM Runoffgroove hf rolloff filters, instead of the single 10k and 22n filter in the 2003 model.
The transistor is used for the relay and bypass board in the 2003 model, BUT the 77 model did not have as sophisticated a bypass. It used a 120k resistor and simple shorting switch from the bottom of the drive pot, 1k, 470p, 12n, 12n, and bottom of the level pot, to earth. When the switch is open all the foregoing components were lifted by the 120k resitor - hey presto bypass mode. when the switch is closed: bingo, tons of boost
Another minor detail, which has a subtle effect on the sound of the original 77, was the addition of a 220k resistor from the inverting input of the 741 to the half rail bias supply.
Personally, I prefer the sound of the 77 model - more mushy like a Marshall. The 2003 model has a more sparkly Fender sound, because of the better top end response obtained with the TL071.
I have played around a lot with this circuit years ago - a NE5534 sounds nice in there too - but consumes a lot more current from the
I'm sure analogguru will get around to sketching the 77 original version eventually, but i think he is a bit overloaded with stuff at present - stay tuned
ps: I have verified both models