my 800 has an extra preamp gain stage and the preamp is reconfigured to be very similar to the SLO.
the power stage is the same sort of thing, plus i used the older JCM800 2205 schematic and copied the PPIMV control out of that into mine. So i kind of have a mot rodded JCM 800 2205 with a PPIMV, which is like a 50 watt Avenger.
I also Added a depth control using a schematic sent to me by Bill @ soldano, and removed the reverb circuit.