Can anyone tell me if you can get or replace the ceramic sockets for the bulbs that go in the center shafts for the heating knobs & the cups that go in the face plate that often seem to crumble up?

The only way to replace the crumbling cups is to replace the whole panel assembly.

I scored a NOS one on eBay a few years back when I was running my 240D.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Thanks for the response. Was wondering if the bulb sockets can be possibly secured from a electronic supply house or some kind of led light would work in their place?

I would try a wrecking yard first, that socket assembly is pretty common across many M-Bs.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Thanks for the help on this Jay Bob! I found a unit in a '78 Saturday. I think the switches might be the same as the '83's?? Do you recall if you can change out the switches in the panel without taking the dash off?

On a 240D if you pull the glove box liner and the gauge cluster there is enough room to reach in behind there to work on the heater control switches. Also pull the rocker switch panel (it is just clipped in) and the radio to really open things up.

Wear gloves, lots of sharp edges back there!

However they made a change between 78 and 83. There is one airflow director lever on a 78 and two on an 83 so the panels are not compatible. I think the rotary knobs are interchangeable. Also the AC controller in the upper panel is different.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech