So there's countless threads about this topic, and I've read, I don't know... 20 of em out of curiosity.

I haven't seen anyone say this so maybe this'll help another retard like me: if your w123 300d has a cruise control module, just unbolt it from its base (just 3 easy bolts or so) and move it a few inches away from the engine. This way you don't have to lower in the valve cover like its a damn puzzle with the gasket catching on this and that. Just move the damn cruise control module and the valve cover goes in directly and easily.

Also, no leaks with a victor reinz gasket. No sealant used, just very clean mating surfaces, and made sure the gasket was really on the valve cover. Used crush washers too.

Edit: I also shaved down 2 of the 4 'shoulders' of the valve cover (the two driver side ones) a fraction of an inch... Probably 1/16 of an inch, maybe less (those were my two problem areas for leaks). Just felt that when tightening down the valve cover, it was bottoming out and wasn't really compressing much of anything.