Hello and 300TD Question
 

hi, I'm Zac and I'm new here.
My wife and I recently bought an 84 300td with 166K on it. Yesterday we were starting the car and in park it wouldn't start. The battery power seemed fine and the glow plug light was coiming on ok. I moved the shifter around and when it was in drive it started right up like normal. On the way home we stopped at the store and I left the car running. I went to put it in park and it was slipping and rolling down the slight grade in the parking spot, making a clicking noise like it was trying to "catch". Any ideas what this might be. It's making me very wary of its reliability.

thanks in advance for your help.

zac

It sounds like you have a problem with the bushings in the shift linkage. Basically, the position of the transmission and the shifter do not "agree." If you want to fix it yourself, do a search here and you will find more info.

Neutral safety switch
 

Not starting in park could mean your neutral safety switch. Try starting in neutral. Regarding the "catching", my tranny does the same thing. It is the parking pawl trying to engage the notch that it goes into, to lock the transmission up. To prevent further wear to this part which is inside the tranny, always use the parking brake. If it is out of adjustment, it is really easy to fix. You want your parking brake to work correctly as a matter of safety. This way you don't have 3,800 lbs. of Mercedes being held by just the tranny when it is parked.