Series 2 engines use a cover, similar in function to the timing cover on the front of them, with a pressed-in seal for the rear.

An excellent picture source is in the post that illustrates rebuilding an L36. Curt Martin authored it, and IIRC, a few pictures will show the rear of the engine, and a clear shot of the plate you asked about.

Thanks Sandrock

I did not know that that rear main seal housing was back there.