John , here is another tip you may want to try before you pull the trans, seal off your breathers etc on the rocker covers. apply an old reversed vacuum cleaner or low pressure air source to the
oil filler cap. Remove the dip stick to allow most of the pressure to escape and apply some dishwash/ liquid soap & water mix to any suspect areas like the valley gaskets etc, any leaks should show as bubbles. Do not use excessive pressure or you may create a few more leaks.
Jac Mac