I bought a catch can on Ebay and installed it on the 240D and it really helps with the oil that dribbles down into the engine before starting each morning it still leaves a cloud but it's not like a smoke bomb each morning. It's a square can with two angled 45 degree connections (like an old AA gun battery) and it works (but does leak a little) since the sealing isn't all that great.

I have another design which I got for free due to a damage claim but the holes don't allow much blowby, if you have a drill press you could drill out the connections and you're welcome to have it if you pay for shipping.

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1974 240D 3.0L 4(M) - 250K -OM617.910 + 300D FW + Rajay turbo power!
1977 6.9 3(A) - 84k