Cabin AC filters ahead of the glove box!!! I don't know how to check the activated charcoal filters. Easy to get to, then what?

How about ATF and filter?

Remove the TCU, second module from the front in the starboard side electronics box, and set it connectors down in a pan overnight. If there's no trace of ATF, keep rocking. Otherwise, open it and spend a can of electrical parts cleaner rinsing off ATF.

Is the turn signal switch fixed or does it move independently of the steering column? There's a clamp ahead of the clock spring that comes loose.

Not vehicle specific but flex joints and diff fluid.

Sixto
98 E320s sedan and wagon