Lambda Sensor - Where is it

[TuscSam]

Where is the Lambda sensor on a Speed Six MK1 Tuscan, are they easy to replace

[NCE 61]

They are mounted in the boss just before the catalytic converters

[TuscSam]

so I need 2 if needing to replace, are they easy to fit. I have seen 2 types one on trevor clever with a white round end connector and one on ebay with a grey plug connector, which one is correct type for mk1 speed six 2002 year