O2 Sensor Question

[TiberiusBoxster]

I am replacing all four of my O2 sensors. I ordered some off of ebay. The pre-cat ones were the correct oval plug, but the post cat ones came with the square plug. Mine are all oval plugs. I have looked at Mike Focke's O2 page and he has:

986-606-127-01 2000-2002 in front of the starter catalytic-converter

986-606-128-01 2000-2002 after the starter catalytic-converter

The one I bought that fit the pre-cat is the above part number. I can't find the 986-606-128-01 part for around the same price. My question is can I use the 986-606-127-01 part for post cat? Is there a true difference in the parts?

I appreciate any help.

Thanks,
Chris