Just completed replacement of the NSS on 77 300D. No problems, jacked the car from the left side, as stated in previous posts, 2 8mm nuts to take out, unplug the electrical connection, and obtw, take out the 10mm bolt and nut that holds the linkage to the transmission and linkage comes off easier (ask me how I know). In replacing, there is a black plastic ring that has 2 slots that the linkage must fit back into, after a couple minutes of looking at the old one, i moved the slots and all went well. Before dropping jack, I followed guidance from posts and put car in reverse, turned on switch and had back-up lights. Total time about 45 minutes. Wife is happy. An for all the safety minded folks, I used jack stand, parking brake and chocks. All of the knowledge shared here makes life a little easier and less expensive.
Thanks
Ron