I have some of the NOS black ones in a box. I had the red ones but a well known MB classic restorer and YouTuber bought me out at $85 each. It had me scratching my head but I’m happy to take his money.

Your valves are likely good. I restored mine by carefully drilling out the tubes and JB Welding 1cm stubs of MB plastic vacuum tubes in their place. They still work well as verified with a Mity-Vac when hot. So now my smog exempt diesel has functional EGR.

In your case, yes, I get it you need your emission control system working. I’d try fixing your valves.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 190k miles
97 C280 150k miles