Just got this Monday. Mark IIB SR with the MS-12 speaker, RP9C preamp board. It was listed as an 82, but looks like an 83 on the bottom of the chassis, plus the black knobs and 9C preamp lean late 82-early 83.
I played a Mark IVb wide combo with an EV for years, and traded it on a new Mark V 90 combo a couple years after they came out, that I stupidly sold a few years ago. I went to one of the Denver GCs that showed to have a used MkV in stock as well as a new VII. Got there and they sold the V, so I tried the VII, and this IIB was sitting next to it so I plugged in and WOW. I did like the IIB mode on the VII (liked other modes too, but would rather have the V for the tweed and MkI modes, wattage modes and solo volume). I quickly dialed in a nice clean tone. I left it though and after some research went back and made an offer the store manager accepted so I brought it home.
I have read on many forums that it's hard to get both a great clean and lead tone, and the lead mode gets pretty muddy. Not the case on this one, but I'm not a metal or chugga guy. I dialed the clean to sound exactly like my AN SSS. Even better when I ran it through the Hi-tone eclipse 2x12 with repro crescendos. I love this amp. It is in really great condition other than a bunch of dust that I cleaned up after I took those pics. I opened it up just to make sure there wasn't any funny business going on, and to see what rev the preamp was. Appears to have the original preamp tubes and it also has the sought after STR 454 power tubes. I have never owned a Mark w/o the GEQ, but not missing it at all on this one. And the reverb is great too.
Not sure if it has been serviced, but the caps appear to be in good shape with no bulging. I will check with MB to see if it has ever been sent in. I should get it checked out, anyone know of a good MB tech in the Denver area (had a great one in Dallas)? Also looking for recommendations on an after market head shell for down the road. I haven't gigged since I moved to Denver, so it's fine as a heavy ass combo for the house, but not sure I wasn't to lug it around when I finally get around to finding or starting a band.