1993 D21 oxygen sensor

I have a 93 Nissan D21 V6 4x4 extended cab that I had the exhaust system replaced and they didn't have the oxygen sensor so I just took the truck and figured I'd put it on myself. Well the time has come and either they've taken it totally out or I cannot find the location in which it plugs in, any help would be greatly appreciated so that I can get this taken care of. Soon to be the sons truck, so I'd like to make sure it's good to go when the time comes. Heh more work to be done though :|

thanks in advance.

not real Shure but look at the exhaust manifolds them self it been a while since I changed 1 like 8 years ago I believe there is 1 on each side

Thanks Rusty. If I'm correct there are two or supposed to be; one on the manifold and one below the cab and the latter is what I'm referring to. I'm sure it's supposed to connect up top as the cord is longer so that it'll reach up but where to I'm not sure. I thought I found the location but when I traced it back it went to the bell housing.

I may have to give in and go to the dealer and see if I get a moment of a mechanics time that may recall where this stuff is located. That or maybe AutoZone may have it on their computer.