I have a 97 Civic. My stock manifold had the primary heated O2 on the #3 runner. Placement of the O2 doesn't necessarilly correlate to it being heated or non-heated. OBD-I cars for the most part use 4-wire heated O2's. The only cars that I have seen non-heated O2's on were non-OBD, or OBD-0. Your P28 will have no problems running a 4-wire heated O2, unless it's been modified to run a single-wire O2.