The transmission on my 79 450SEL is also leaking pretty badly - leak is coming from behind the neutral safety switch, so I bought a selector shaft seal and will attempt to change it next month. The seal is an MB original part and is a thin ring (30 mm OD) made out of black rubber with no metallic reinforcement or ring, so it may be held in place by either a circlip or the the safety switch itself - P/N is 115 997 074 0... I wonder what gives, because the seal in the below video appears quite wider and press fit.

Can anyone confirm that the selector shaft can be removed without removing, or lowering the transmission?

Also, this video applies to the newer 722.3 trannies, I hope it's a similar process for the removal in the 722.4 transmission on my car (although the oil pan is smaller and does not appear to give the necessary access to unbolt the selector shaft):
https://www.youtube.com/watch?v=KUzBeXCPPBI