The six casting numbers are 14, 15, 17, 18, 20, and 22. Most - possibly all - cars imported to the USA in 1986 and 87 have the 14 head. From 1990-95, they came with the 17 head. If you bought a new head after roughy 2000, it will be a 22 head. The other three casting numbers (15, 18, 20) are very rare and so far I have only heard of ONE of each in the USA!!