Mark was correct, it was the pressure plate/clutch disc rusted to the flywheel surface.
The trans was pulled and a long prybar used to free things up.
I still am amazed at how quicky all this occurred, it happened in less than 60 days. At least one third of those days were rainy ones with high humidity in between.
LESSON LEARNED:p
That is what I got for not garaging the car. I will try to avoid this by operating the car frequently from now on, and if my starter motor ever fails again (knock on wood) I'll be sure to fix it right away.
As a side note, while it was up on the lift, I had a 3.07 differential (out of a 300D turbo) put in place of the 3.46 unit yesterday.
The car really is a nice runner now, the 4-banger was wound up pretty tight at 75 MPH before this, now it likes to cruise at those speeds!
I have a small VDO Tach to install on the dash but I am waiting for nice weather and some warm day I'll replace the dash with one that came out of a 1976 300D - I'll welcome the addition of some wood as well as NO CRACKS!
DDH

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!