The first prototype Dual Rectifier.

[Neptical]

Per one of the videos posted [Mesa Boogie Factory Tour -http://russomusic.com/t-mesa-boogie-factory.aspx] over in the Mark forum by a fellow board member.

Here's a picture of the first prototype Dual Rectifier in a Mark IV chasis:

Question: Were they originally going to add GEQ like the Mark series? If so, why didn't they keep it?

That would've been pretty sick!

 

[4Eyes]

no, it was only test chassis, the mark IV prototype was also built into that chassis (and then the recto prototype)