I would start with the bare essentials to make sure the engine fires up and the car drives.

try the glow plugs, glow plug fuse and plastic housing,the glow plug relay.

establish what type/brand of brake calipers you have.
you can get junkyard finds for cheap and open them up. If the piston bores are decent and piston sides are excellent smooth,then rebuild them ($20 kit each) and keep as spares.

Think about smalls like certain bolts etc. Like the nuts to hold down the oil filter housing cap. (ever drop one and never find it?)

Emergency flasher relay.

look at parts online stores for high priced smalls that you can pull at a junk yard.

brake vacuum line etc..

;)

A little over a decade or so ago I use to tell a lot of my customers that were looking to buy w123s to go ahead. They're easily rebuildable and there's plenty of parts available. But, most people always would always opt for a less expensive after market part rather than the more expensive OE part. It's probably not cost effective to continue to manufacture quality parts to a small market. My customers that were into serious restoration didn't care about the cost, but the everyday drivers would always complain about the price of OE parts. I've seen it on all of the MBZ forums in the last 25 years. Everyone looking for cheap deals on parts. So, IMO, I think that a lot of vintage car owners did it to themselves by being too cheap to pay the price. To this day, I have a good inventory of W113, 108,123 and 126 parts that are NOS still in the MBZ or bosch boxes that people still want for nothing.

Appreciate that!

The aluminum radiator in my SDL gives me hope. If there is enough demand for these parts, perhaps someone will make them. Barring that, I always wanted my own machine shop.

By the way, greazzer is closing shop on his diesel fuel injector services in Sept. But uncle Ken just posted a vid indicating that he has cut a deal with the German company that used to make Monark injectors and he now sells the rebuild kit. No idea whether the complete injectors are also available.

I agree that OEM parts are the way to go,when available.
I preferred that over the years. But lately even some are outsourced to India etc.. and spotty.
Anyway, at least for now,the less expensive after market stuff is a hold over when in a pinch.

This is absolutely correct; people want the best quality but want to pay zip for it. I'm aware of other German companies involved in other product lines that produce top shelf quality products at a price, of course. Cheap skates should go buy a Ford, GM or Chrysler, MB is not for them......

I do believe that MB sales people could have done a better job of explaining to new MB owners the requirement for using genuine MB parts. Most of the MB sales people I talk to only care about making a new car sale. After the sale, they don't care what happens to the car.

Of course, the moment you start putting sub-standard cheapie parts on your Mercedes, it is no longer a Mercedes.

Also for the newbie, get some vacuum shut off valves for shutting the engine off.
Junk yard finds are good if you test them and they have no oil nside.

About 4 years ago, my mechnaic installed a new bosch shut off for my non-turbo 300d.
Alittle over a year later it failed. Just over the warranty period.
So I had him install another new Bosch unit.
Luckily this second one has lasted so far!
BUT I went ahead and pulled serviceable units off junk yard cars so I have 2-3 spares to hold me over...

They ain't cheap new,but I am willing to buy OEM and use OEM used ones as well!!

I installed a clear fuel filter inline just beyond the shut off valve in order to show any oil residue beginning to pass through as a sign of failure onset.

That is the sure way to know in advance of complete shut off valve failure.

great idea!