interesting.

1989 Toyota Cressida

drain plug on pan - yup
TQ converter drain - why do you design it so that you have to take the tranny apart to drain fluid?
filter - what?
it probably is the lack of filter that makes Toyota ask you to change tranny fluid every 2 years or 50,000km at best. Flushing does the tranny good.

1992 BMW 525i

drainplug on pan - yup
TQ converter drain - this guy says no.
filter - yeah it's there somewhat.

no idea about the service life... sold it before i even get to find out.

Never heard of these items getting replaced at all from all the AT cars I've owned. But there is no such thing as a trusted Mercedes Indie around my area - any shop that actually hoists up the car and take it apart like to rip off Mercedes owners because - well it's a Mercedes it's just bound to be horrid to repair, they think, and I agree with them most of the time, unfortunately.

meh I'll just drive around keeping the fluid at the right level and test Mercedes about their "Fill for life" claim.

and save up for a proper dealer fluid service later.