89 burb O2 sensor question...

[jumbo]

i have an 89 burb with the tbi 5.7. It now has headers with straight pipes to mufflers (no more cat conv). I've heard that the O2 sensor in the manifold on the driver's side plugs into the cat con, is this true? What i'm asking is if i don't have a catalytic converter anymore, does my O2 sensor need to be plugged in to anything, like the harness going to the ECM? I can't get it running, i'm trying to work on someone else's hack job, and i can't find a place for the O2 sensor to plug in. Please someone help me eliminate this as a possible problem...