73 280SEL 4.5 stuck in park....help!!!

A couple weeks ago I came home and parked the "Silver Bullet", my 1973 280SEL 4.5, in my drive as I've done many times. Living in San Francisco, my driveway is quite steep, and I always back in. The other day I went to drive the car and could not move the gear selector (automatic, steering column mounted) out of park. I thought that the car might have rolled forward placing stress on the tranny, but I disconnected the linkage at the tranny, and I still could not move the lever out of park. Anyone ever had this problem?? I need to move it ASAP as I anticipate having the freshly rebuilt engine back in my 500SEC any day now and I wanna drive it!! See Photo