Does the Dealer really support the 81-85 300D anymore--why I feel its "No."

[Carrameow]

The W123 300D is actually a rarity at the Dealer now and many of the dealer mechanics, if younger than 50, may have very little experience on them.
Most of the dealer's service population are cars between 1997 and 2007 and since then training techniques have greatly changed for dealer mechanics. They are now just as highly specilaized as the chip technology in modern day cars and there are very few "Generalist Know it All" Mechanics that can service a wide range of problems on a car.
Add to this the fact that the production run of modern post 2000 Mercedes is very brief--you just dont have the lengthy 9 year run that produced the huge population of 78- 85 240D and 300D's today. The average run is probably three years.
Some systems, like the vacuum CLS or diesel IP tuning may be a total mystery to a modern Mercedes Dealer mechanic.
I mean, how many 300D's come in per day now? Maybe one or two against 50 cars a day. My bet is you will find more expertise on this forum on these cars at the Mercedes dealership.
I am being very reasonable, and not cynical, about this. If you dont believe me, go in and maybe query a shop mecahnic about your 300D. Go ask them technical questions about the car; ask them about troubelshooting the CLS, or IP timing or, or changing the rear CV boots, why the cluster invariably stops at 220K, ask them about the ALDA or whether you should rebuild your vacuum pump or what the diagnosis steps for your cruise control are. You will be really surprised, I bet.