I think in your car the EGR valve sits on the intake manifold behind the that good old 4A1. A couple of bolts hold in place. It might be a tricky reach with a spanner because the vacuum canister blocks direct access to the bolt heads. I think on the 280E the EGR valve is on the exhaust manifold and there's an addional pipe to disconnect with a big wrench.

Sixto
83 300SD
98 E320 wagon