On My 300d 1981 There Is A Round Plug Of Some Sort On The Side Of The Block Across From The Fuel Injector. Oil Is Leaking From There. What Is This ?plug? Can It Be Changed. Is There A Way To Stop It From Leaking. Can It Be Changed Without Removeing The Fuel Pump. The Engine Is Great But It Leaks Oil And Is Messy. Thanks

sorry i couldnt figure out where the plug is. could you be a little more specific? your description seems a little contradictory to me.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

If you are referring to the large round plugs (almost look like pipe plugs, about 1.5" diameter) with the large hex shaped hole in the center, those are coolant plugs, there should be 3 in a row, (one will be a reducer with a temp sensor in it). They like to rust into place, but you might get lucky, they take a 17mm hex socket. They are a straight thread plug with a sealing washer (like the ones used on banjo bolts) Not sure how oil could leak from it though, sure it's not thickened coolant oozing?
Those are the only plugs I know of in the block by the pump. There might be some oil gallery taps down below the pump, if there are they will be centered in the "raised hump" that runs the length of the block casting to the oil filter.