Let me say first I'm no expert. Second I've never had a final drive off my Long. But I'll tell you what I saw when I looked at my 2610 and my neighbors 510 Long and hope I'm looking at what you refer to in your question.
The angle bracket that the chain stabilizers connect to are at a little angle with the bottom of that bracket more to the rear of the tractor than straight up and down. The oil fill plug and oil check plug are pretty much one over top of the other straight up and down. Down at the bottom behind the stabilizer bracket is the drain plug for that drive. It's at the bottom center as best as I can tell. I also noticed on both tractors there a mold line in the final drive shell that's straight(horizontal) from front to rear.
If this doesn't answer your question you can reply and I may have to take a picture and send it to you by e-mail. Hope this helps.