I have a 1965 John Deere 3020 gas row crop that I'm changing the hydraulic and transmission fluid from 303 to HyGard. I checked my operating and service manuals which said there were two drain plugs. One small square plug on the side of the transmission area and the large square one in the drawbar frame. I've always only drained the large one and filter and didn't even know about the small plug. When I took the small plug out with the large one still in the frame there was only a few drops of fluid coming out. Got about 7-8 gallons when I opened the large one which is normal. Anyone know what cavity the small plug drains and should fluid have drained out of it? I hate to put 8 gallons of HyGard back in if I have a problem internally. Far as I could tell, there is only one fill area on the right side of the seat. Set me straight, what am I missing. John Deere service techs had no idea what I was talking about...guess too old of a tractor for them. Happy Easter.