How do you ascertain that? The two units are interconnected. You need to keep both full, but the oil circulates between them.

Transmission was leaking, checked gear oil and transmission was way overfull, and had to add gear oil to OD unit. ran the car for a couple of days, Still leaking checked gear oil, same result. I know that they are interconnected, I am puzzled. Thought maybe someone else might have an idea.
By the way I enjoy your column in the WTN.

It could be something perverse, like badly cut gasket covering the holes in the adapter assembly, not allowing the oil to circulate properly.

That is what I was thinking, but didn't want to think that, as I have just installed it and the engine in the car. I had the idea of running some tubing between the fill holes of the od and tranny so that would allow the level to stabilize. However while I was looking for fittings etc, I figured that I'd better check to see if the fill plug holes were at the same level....NO THEY ARE NOT !
The od fill plug is about 3/4 of an inch higher than that of the tranny. So I am going to leave the oil level even with the fill plug on the tranny and road test it. Every time I filled the od to full, it overfilled the tranny. Road test tomorrow, will update.

Road test completed, fill od side to same level as transmission, no problem. OD level approx . 3/4 inch lower than transmission