The early M110's had a vent on the lower left front of the engine which connected to a plastic line that led to a cannister in the trunk. In later blocks, this was replaced by an oil pressure relief valve and the vent hookup was moved up under the AC tensioner bracket.
I am not sure if this is specific to my 280C, or if it carried over into the later engines, but the banjo fitting and tubing are shown in the 280E parts book.
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe