I have a 1984 300SD & it has developed a "groaning" sound when I turn right. I jacked it up & with the car running turned the wheel, no sound (most likely because it does not have the weight on it). I grabbed the tire I turned the tire hard manually & got a little noise from what I believe to be the "Guide Joint" on the top of the Steering knuckle. It looks to be in great shape. Any tips to solving or isolating the problem? I also have not been able to find a replacement part. Probably because I am not calling it the correct name (limited documentation from the few manuals I have. Secondly, my car has developed an engine "wobble". I can feel in the front seats at an idle. It started after I took the bolts out of the motor mount & engine shock to replace the oil return lines. The motor mounts & trans mount looks ok (all are pliable rubber & vibration/wobble does not seem to be transfered to frame). I seem to have read somewhere that the mounts can "get soft" over time & need to be replaced. I have done a diesel purge, the engine shocks & the mounts look fairly new (replaced in the last 3 or four years or so). The car does not smoke, starts up right away & runs smooth even at 80+. I am only getting around 20mpg. I am wondering if it could need a valve adj.