5x114.3 is the metric equivalent to 5x4.5, which almost every car used back in the day, so you can search for that size too. Most modern Fords use the 5x114.3 wheels, not just Mustangs (my 2012 Fusion does and so does my 2014 Explorer). Just make sure you get the right offset.I think most mustangs are this size. I just put in a 2004 mustang cobra, and it appears to have 5x114.3 wheels.
And how does one know what the correct offset is?
.
What company did you get the spacers from?