R32 GTR o2 sensor front vs rear.

[Fizurg]

I’ve got a stock standard 1993 R32 GTR. 
I’m putting twin turbos back in and I’ve come to putting the o2 sensors in and realised they have different plugs. One is more square and one is more rectangular. 
Which one is for the rear turbo and which one is for the front turbo? Or is it a case where the ecu doesn’t care?

[GTSBoy]

The ECU does care - it runs the engine as two banks of 3 wrt O2 trimming. So you have to give it the right one.

Um....look at the engine bay pictures in the GTR manual? I think you can make them out there. I think the physical wiring diagram might also help....

Actually, I just looked at the engine bay wiring diag. It clear shows the shapes of the connectors. I'd say that R means rear.

According to the rest of that diagram, pin 2 of the R one turns up at terminal 55 of the ECU. Which is.....the rear one.

[Fizurg]

You’re an absolute legend man. Cheers.