You're looking for the 1990 Ford Mustang 5.0L V-8. It's a Bosch unit with metric threads and a dab of anti-seize already applied. Parts counter guys might tell you there's more than one to choose from because (1) some had different length leads, but that doesn't matter to you because you're going to cut off the Ford connector, and (2) some of the cars had two O2 sensors, but you just need one.