Just fyi, I'm running a set of Hawks 1 5/8" long tube headers w/ 3" collector and a 4L60E trans. On the passenger side header the O2 bung is on the top-inside of the collector and there's no room to get the O2 sensor in between the trans and the header, so my plan is to plug the existing hole and drill and weld a new one in place on the inside of the collector, basically parallel to the ground, in front of the trans pan. Maybe there is more room with the manual trans. Also the collector is right up against the passenger side frame rail, I massaged it with a crow bar and I think I barely have enough room to get a band clamp on it now. The driver side fit great though, no troubles with O2 sensor fit.

 

My pass side o2 fits ok. it is very tight though and looks like it would hit the servo cover but it doesnt. Im running a billet servo which i think sticks out alittle further than the stocker. Dont see any reason why yours wouldnt fit too.

 

1 5/8" headers are the chinese knock offs and the O2 bungs are in different spots. The SSW headers will clear 4L60E/80E no problem, knock-offs require the pass HO2 to be moved downstream