Had my new to me 84 300sd for a month and frankly am missing my 79 a bit. I have just begun to try to start sorting out its issues. The most serious is that the rpms will not go over 2000 to shift (except for when it flairs up to 3000 during the one to two shift). This is the same if the car is hot or cold. It basically behaves like gentle accelleration even when under hard accelleration. The only way to get the rpm's higher before the shift is to put it in D.
There are several vacuum lines missing. Two on top of the valve cover and one on the assembly near the master cylinder. Where are these things supposed to go to? And is this the source of my shifting woes? This car is getting a very dissapointing 21 mpg. which is 3 less than my 79 300sd.