I'm trying to determine the specific date that Ford ceased production of the '98's, and began building the '99's. I'm fairly certain that it was sometime in October '98, but haven't been able to pinpoint the day. Rumor is that Ford built some of the late '98's with P.I. heads, but nobody can seem to verify this. It seems likely that if they did install the P.I. heads on some of the '98's (which I seriously doubt), then it would be the late model run cars. If you know anything about the supposed stock P.I. heads on the '98's, or if your car was built in late '98 (as a '98 or a '99 model), please post your info.! Thanks.