1978 300SD Oil Leaks

I've been running through a lot of oil lately so I had my engine cleaned thoroughly and ran it at idle for 30 mins. I noticed that oil was leaking from the grate at the bottom of the transmission, but nowhere else immediately noticeable. I suspect that this is the dreaded rear crank leak that requires engine removal, but would appreciate confirmation before I go out and solicit estimates. Am I correct?

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