OT: 1993 Audi 90. 02 sensor control - post cat

[talltorontoguy]

Hoping someone might have some thoughts on this one.

This car (2.8l v6) requires 4 02 sensors, 2 pre-cat and 2 post-cat. The 2 post cat are actually 02 control sensors that override the two pre-cat sensors.

Anyway, the pre-cats can be replaced with bosch generics, or the ford mustang ones like we do on E34's.

I can't find a replacement part for the two post-cat ones. They're 4 wire sensors, but I don't know if a generic 4 wire will work or if there is a special requirement. The dealer wants over $250 each for these... so I need help.

Let me know if you find something,

Rod