Michael, the drain plug is magnetic. If you drain the transmission rather than
pump it out, you'll get a chance to see a Christmas Tree early. The metal
grindings cling to the magnet like a tree. Those fine metal grindings will
tell you a lot about the health of your transmission. If you feel the metal
between your fingers they should be smooth and bit free.
Another good reason to drain the transmission though the drain hole is to get
the bottom sludge out. If before you drain the transmission, you take the van
for a few mile drive in low gear, you can warm up the transmission oil and
churn it up a bit. This will speed up the draining and improve your chances of
draining the sludge.
I elevated the front of our van (a syncro with its own idiosyncrasies) and
left the transmission draining for 2 hours. It was still dribbling when I
plugged it back up and refilled.
-Larry

Michael Townsend wrote:

> OK,
>
> So if I drain all that I can with a hand vacuum pump, do I put in a
> measured 3.2 qt, or do I just keep filling until it starts running out of
> the fill hole?  Can you overfill these things, if so, what happens?
>
> Thanks,
> Michael Townsend