A former co-worker of mine was driving carpool and was driving his wife's brand new boat of an Olds, RWD with a big v8 while his Mercedes was in the shop. His Mercedes had the four speed column shift, and the Olds was an automatic. At the top of the onramp, he instinctively went for third, and park did engage for a brief second before it sheared the rear of the trans case. Sometimes they do engage-

As for the original question- Shift linkage bushings. This is a known issue, I got mine with "transmission problems" because of these bushings, I drove it for a couple months then parted it out. Use the parking brake, if your bellows seals on the cables are in good shape there won't be any freezing problems.