The parking pawl on these late 80's trannies are massive. My 560SEL also rolls about 6" when parking on an incline, which is consistant with the spacing of the pawl notches. Sometime I use the parking brake, sometimes not. When I don't I simply hold the brake, and ease it off until the pawl catches.
The 4.5 is another story, I always always always use the hand brake on that one even when parking on level ground.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.