Lee1940

OP here, For what its worth, my local transmission shop says they drain the pan and hook a machine to the tranny where the filter goes, start the truck and use the transmission to pump the fluid through the system flushing all the old fluid out. No high pressure used. Sounds reasonable to me.

RLXXI

Did they mention possible transmission failure afterwards due to the high mileage? Probably not because they build transmissions and would love to build yours when it does fail.

Your truck and if your willing to take that chance go for it but you have been warned.
.

sdmartin65

Drop the pan throw a new filter in like others have said but install a pan with a drain plug. Going forward you could drain the engine oil and trans at the same time. The filter in the trans doesn't need changing as frequently as engine oil filter so that part can be done on a longer schedule.

SCORGE

Yeah..
Drop pan, change filter, clean magnet, clean pan, replace lost fluid.
Put in a pan w/plug for easier drains