The Mazda MX-6 had a few different versions, such as the DX, LX, and GT. This is the GT model that came with the 2.2L Turbo engine. Which is the same one found in a Probe GT (that I also found at the same salvage yard).
Other than being the GT model, there's not much that's special about it. Though the power and torque output from the GT model greatly differed 145hp vs 110hp, and 190 ft.lb vs 130.
The GT came with 4 wheel disc brakes, optional ABS, and electronically adjustable suspension. This one apparently had the optional automatic transmission too.
It also only made it to 156k miles. (while the Probe GT I found made it to over 200).
Looks like the previous owner painted the valve cover.