Replaces GM 12559890
Billet 6061 T6 aluminum.
Replaces ONLY GM 12559890
Does not fit F-Body LS1 engines
If you have GM 12559885 then you need to
purchase the other LS1 listed on the website
This is not an underdrive pulley.
Not recommended for re-installations.
Use proper installation tools. Pulley has a press-on fit.
Same as stock size.