Two different S14 Catalytic converters??

[SauN]

I was changing my old cat. because the flange started cracking, and I got everything off ok. I went to go compare the old catalytic converter with the "new" used one that I got and test fit everything to make sure it would line up with everything in the car. So I'm test fitting the 02 sensor in the "new" cat. that I got and it pretty much fell right through. And then I compared the two converters and this is what I saw....

(the old converter doesn't have the flange)

The size is noticeably different...


I'm thinking maybe it was a different between the OBD I and OBD II (I have a '96), but i didn't think OBDI had a second bank 02 sensor. I don't want to go out and buy another 02 sensor jsut so it can fit the new cat...I know some of the guys who have bought aftermarket headers found that the second 02 sensor hole had been too large and they either 1) left it out and plugged the hole 2) replaced it with a 200sx primary 02 sensor or 3) used a reducer. I'm probably going to use a reducer. Does anyone know the exact size reducer i need?

[projectRDM]

95-96 uses a smaller pitch 3wire sensor, 97-98 uses the larger pitch and it's a 4wire unit. You have one of each.