D7 7m engine oil loss

Not familiar with that block, but, with the pony removed is there a small access plate on the diesel engine skirt? Loose or missing bolts there would explain it

I don't know the book doesn't show anything except that the pony block goes against the main case to have the back section of the pony.

My engine appears to be completely self contained and does have a separate dip stick. That is why I am puzzled by it. If it was like your 17A I could sorta understand. Aaron

Have you ever had the pony motor off? That shared wall is where the patch goes if either the main or pony throws a rod.

Have you ever had the pony motor off? That shared wall is where the patch goes if either the main or pony throws a rod.

maybe gas leaking into pony crankcase , diesel some other issue ?

I have not pulled the pony engine off to see if the is a patch behind it in the main block. It is not gas getting into the engine also.

I can't think of any other way oil could transfer other than through the pony transmission coming from the main flywheel housing but you state the pony clutch housing is dry so that kills that route.

The main flywheel housing is, or should be dry on a D7 of this vintage, take the cover off and look inside.