I tried to post over on RT but got a 504 timed out message. Here's what I would've posted -
It looks like the real deal, except for the aftermarket head shell. I can tell from the lack of dovetail joints. Mesa cabinets are joined together using a dovetail joining system and they never put a wood brace in the back using that type of screw. The serial number is where it should be to be considered a "factory" C+, not a modded C+. Simul-class, Graphic equalizer, Reverb, that's known as a DRG, and just shy of an X for export transformer which is very desirable for sure.
If you paid less than $3,000.00, you got a good deal.