I got a weird squeak/chirp noise every few seconds, that only happens when the car is in Drive (a604/atx tranny) and at a complete stop. Sounds like something metal rubbing against something else metal. Any movement stops the noise, and shifting into neutral stops it too.

So basically I'm wondering what all spins when the car's at a stop? The crank and torque convertor, nothing else right? If the torque convertor were slipping while driving, I'd notice it, but it's not.

Anyone ever heard of a torque convertor failing on our cars at 120k miles (maybe 200k given the abuse it's been through)? Or is this a bearing somewhere?

its possible the torque convertor is going. When it does the thrust bearing and shaft bearings allow the plates to grind causign a squeelign or grinding sound as if two flat pieces of steel are spinning on top of each other. Could also be the bolts loose on the flexplate.

Torque convertors are notorious for failing on the powerstrokes (ford) and this is one of the telltail signs.
Terry