I have tried to contact PAC with two emails, and on their site, also. They have not answered me in either place. My camshaft maker recommended the springs, and he won't tell me what retainers work with those springs. The seller finally sent a part number, but it is for steel locks. There are square locks, radial locks, traditional locks, super 7* locks, mini 8, 10*, super 10*, just for starters. Everything seems to be geared towards the LS, Hemi, Coyote, and for lightweight titanium, or beehive, 11/32" is "old school". Joe-JDC