How often do you change trans fluid?

Just wondering how often it should be changed i know the book says between 50 and 100k. my van has 63k and am thinking of doing it this summer. do you just drop the pan or do you take it somewhere for them to pump the fluid out of the tourqe converter?

you have to drop the pan since there is no drain plug.
If it was up to me I would change fluid and filter this time. After that I would just pump out the fluid and refill through dipstick.

i think it should come with a drain plug from the factory. changing the tranny fluid is so messy.

I've read here that a number of people have had major transmission failure shortly after changing the ATF... can any one confirm this??