I just checked the instructions again and it says, "Install cooler in a position which will insure it is filled with oil at all times and will not drain back to sump." I guess this could be interpreted to mean that if I place the cooler so the inlet and outlet fittings were on top of the cooler then oil would stay in the cooler and not drain out when not in use.
Thanks for your input!
Another question: Sometimes I don't think these things through enough.
Do the lines going to and from the transmission
carrying hydraulic fluid need to be high pressure hoses?