O2 Sensor wire disconnected - 1994 K1500 350 TBI 4L60E

Hey everyone. I need some help with finding a wire. Service manuals have failed me, this is my only mode of transportation at the moment, so I need to find a solution if at all possible.

I have a new-to-me '94 Sierra and I cannot for the life of me, find the lead for the O2 cable that the sensor cable would plug into! The truck has had a lot of DIY work from what it seems. So I might be out of luck entirely, we will see!

To clarify, the O2 sensor has its harness and plug, but they are dangling and disconnected. The exhaust is "Y" shaped and there is only one single O2 sensor, before the catalytic converter on the passenger side of the truck.

I cannot find the other plug that the sensor wire would plug into, much less the wire it is a part of.

A few questions if you don't mind:
Where would that wire be?
Does it go on its own all the way up to the pcm?
Does it branch out of the main harness on the firewall?
If so, where does it branch out?
Is it on the left or right side of the engine? Does it cross over the transmission housing or is it further up?
What color is the wire?

Any answers to any of these would be extremely helpful. Thanks in advance everyone.

This may be a start. I'd imagine there is a connector near the firewall in the engine bay but IDK.... Maybe peek around back there by distributor/egr area?
Would have to dig some until someone familiar with your truck chimes in....
look in the 94 driveability, emissions and electrical diagnosis manual for some diagrams...maybe something will stand out. looks like there is a connector somewhere you're going to be looking for regardless.

Look under the black "T" shaped cover on the fire wall, it might be tucked under the harness there.

I am having the same exact problem. I replaced the exhaust Y pipe months ago and got stopped by winter weather. Now everything is dandy
but I cannot locate the connector for the O2 sensor to plug into. It should be a fairly long lead as the O2 sensor wire and plug is only
about 10-12" long. But I am stumped. Would the lead down to the sensor originate in the bundle that comes out of the firewall or
from somewhere else? It seems to have disappeared.

What motors do you have. Looks like the 4.3 and the 5.0/5.7 are set up different.

I think you both are looking for a 3 wire harness, purple, black white, pink white wires. Check around your transmission, maybe grouped and there somewhere.

Ha! I got it. The new Y pipe had a provision for an O2 sensor and threw me off the track. The factory O2 position for
my 1993 K1500 is in the exhaust manifold, near the collector, on the drivers side. The wire that connects to it is a single wire
to the rear of of the driver side cylinder head. All is good.

Randy