Dresser TD7G transmission oil

I'm trying to make it a clean sweep of all oil, filters, and maintenance issues with the Dresser before putting it in service. This ain't cheap! Numerous aspects of the tractor differ from the manual. The thing of greatest concern is fluid volume. Final drives needed 2 gallons more than the manual calls for. Transmission calls for 74 quarts, only 43 came out though the dipstick shows full. The oil from hydraulics was clean, and pretty. I felt bad changing it. Transmission oil looks like old engine oil; black. It stinks, but I don't think it's a burned smell. The bottom of the transmission has 5 drain plugs. One in center uses 3/4" ratchet to remove. All others need 1". What does this mean. I DON'T HAVE A 1" DRIVE, BUT WILL GET ONE IF IT'S IMPORTANT. The torque converter looks to me to be a twin to my Case 580K converter. The Case backhoe looks to have identical Cummins engine too. Some 580Ks had a drain in the rotating internal portion of the torque converter, later models did not. This old oil is ugly enough I want it fully drained before refilling with new Hy-Tran from Case/IH.

I'm also wondering if I even have a TD7G. I have only a hand cut decal to say it is. The nameplate has no numbers AT ALL!

Dresser TD7G transmission oil