I have a 1991 z28 5.7 tpi. I haven't been able to check where the o2 sensors are located. I read on here some guys saying there is one sensor located at the y pipe. Others say at the cat. I ordered a set of dyno dons and i told him i wanted o2 bungs welded on them and now i'm not sure if i should have done that. Can anyone let me know what i have? The car is stock but i assume there are 2 o2 sensors that would go in the collectors, I'm not sure.

 

There is one 02 sensor that goes into the driver side manifold/header.