I have a 1988 Fiero GT that I purchased 'as-is' a little while back that had on older 3800 SC Series II swap, from what most likely was out of a 1999 Buick Regal donor car.

It has two O2 Sensors, both with 4-wire leads. Are these O2 Sensors most likely Heated, or Non-Heated?

Thank you for the help.

I believe heated. Only one wire oxygen sensors are unheated .