If the fluid is contaminated with coolant it will be an obvious milky white mess. If not look for  differential fluid or a bad valve body, torque converter or clogged vent.

Dennis,
From my phone.
________________________________
From: Rick Cooper<mailto:rickdcooper@GMAIL.COM>
Sent: ‎2/‎22/‎2015 11:00 AM
To: vanagon@GERRY.VANAGON.COM<mailto:vanagon@GERRY.VANAGON.COM>
Subject: A/T problems -- fluid level high

After having the auto transmission in my '87 2WD overhauled last month, I
noticed the ATF fluid level creeping up. I've only driven the vehicle three
or four times, for a total of maybe 50 miles.  When I checked today the
fluid level was way, way up -- maybe 4 inches up the dipstick!  I'm
guessing the stock cooler has failed, and that I ought to have replaced it
at the time of overhauling the transmission.

What are the next steps now?  Can I resolve the problem (pending installing
a new cooler) by simply taking the stock cooler out of the equation?  Is
this as simple as connecting the coolant hoses together with a coupling or
perhaps removing one and connecting the remaining hose to both connectors,
thus creating a loop?

What about the polluted ATF?  Will a drain and refill eliminate the problem
or do I need a more rigorous flushing procedure?  Any and all advice much
appreciated!

Rick