Changing trans/diff oil 1949 John Deere M

[mr.precision]

Just bought this 1949 M. Pretty nice shape.
Trans filler plug removed - overfull with a yellow creamy colored goop. So it's been used for a long time with water in the trans as the emulsion shows NO separation.
Drained out the mess, and put in a gallon of diesel oil. Drove it around a bit a drained it. Seems to have removed [u:7852ba3c22]some[/u:7852ba3c22] of the goop.
Here's the question - shop manual says 6-1/2 quarts to fill. There's no way it will take more than a gallon. And before I use the high dollar Sta-Lube GL4 oil, I'd like to make sure it's as clean as I can get it. .
So do you think there's 2-1/2 quarts of sludge in the 'box? Would removing the gearshift lever allow a better look in there? And would a gallon of cheap motor oil help with doing another flush? I just don't think the diesel did much.
Thanks[u:7852ba3c22][/u:7852ba3c22]

 

[Hayfarmer]

If you are doing a complete service you might want to drain differentials also.

 

[donjr]

Put a bucket under it and take the drain plug out again. Let it sit for a few days. I have a Super C that I drained, and the rear stopped draining with about 6 gallons of slime. I left the second bucket
under it overnight, and came out the next day to something that looked like bratwursts in the oil....

 

[M-MAN]

I would leave the plug out for a
few days and call it good. The
sludge will drain out and the tar
that's left isn't going anywhere.

Do the final drives at the same
time. I would suggest that you
remove the three bolt cap on the
inside of the final drives and
check the bolt inside going to the
stub axle. If it doesn't have a
good lock it will be loose and
cause whining.