Pitman arm attaches to the steering box on splines.

Standard procedure for truck diesels is to turn this arm several spines one way or another, after about 120k miles. The results directly effect steering tightness, taking up slack and slightly changing the turning ratio. Its something that requires expert skills as turning the Pitman arm too far, or not far enough, can ruin the steering characteristics.

Has anybody had this procedure done on their 123 deisels?

My '79 240D with 115k miles has sloppy steering and this is one thing I'm looking into.