1985 300 Turbodiesel

Symptoms:
Car will not start in park

Car will start in neutral

Car will not shift into reverse from neutral after it is started

Car will shift into reverse after it is started from neutral and then shifted to park and then to reverse

When car is put in park after engine is shut off it can still be moved by pushing it, emergency brake use is a must.

What is wrong?
I think it must need a new neutral safety switch. Is that what is causing the symptoms I’ve described? If not what else might it be?

Where is the neutral safety switch? My Alldata DIY says it’s on the left hand side of transmission in the rear, but I couldn’t seem to locate it. Do you access it from the top or underside of car?