The lower half of the fuel distributor (intake plenum) is actually rubber, probably petrified rubber now. It is on my 420SEL and it becomes brittle just like all the rest of the rubber parts. There is a nipple between it and the elbow you are referring to.

Save yourself some trouble and get the elbow off with any means available, cut it, nibble it away, whatever, without damaging the nipple or the lower plenum or else you will have to replace it as well. The more ya keep digging around in the intake area you will find plenty of other gremlins, rock hard cracked and split hoses, clogged EGR tubes, stripped-out allen headed capscrews, broken coolant sensors,,,,,

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Chas

Had a 380SL, 450SL, 380SEL, 420SEL, 500SEL

Got a Euro 500SEC right now.