So I picked up the AOD, didn't need the 5.0, but for the price it'll get used in a Mustang somewhere. The AOD is pretty clean, fluid looks and smells good, not like a fresh flush. Haven't removed the torque converter, but it looks new. I had to haggle for quite a while, so I mostly believe he has some recent repair money in them. I'll drain the oil, add a fluid temp gauge sender and drain plug to the pan, get a new TC with 2,100 stall to match my cam, and install it if I don't come across any issues.
There are several upgrades which toughen up the AOD: 4340 input shaft, AODE reverse drum and 2" band, AN "A" overdrive servo, and couple extra discs in the forward drum. Lots of work there, which I will probably save for a winter project. I'll just have to take it easy till then.