I'm moving a set of Speed Pro hypereutectic pistons onto bushed rods and I can't find the retainer size listed anywhere. Does someone have a source for this information?

SBC wrist pins are .927 diameter so that's what the locks are designed for. The retainers should have come with the pistons.

I use JE pistons myself. BBC pins are .990. The spiral locks that come with the pistons work from .946 - 1.005

SBC spiral locks work from .896 - .945
SBC c-clip locks work from .926 - .945

It depends on what your pistons were designed for. Personnaly I'd love to use c-clip locks just because they're easier to install and remove but the spiral locks will never fail. There's 2 on either side of the pin. The downside is that if they ever need to be removed from the piston, new ones need to be installed.

Normally I would expect them to come with the pistons. I'm sure these pistons did, five years ago when the speed shop put them together, but they used pressed pins back then and I have no idea what happened to the locks.

So I take it then that the O.D. sizes I'm seeing in the catalogs are the relaxed dimensions, and I only really need to worry about the thickness?

as your shop, they ought to have a box full laying around.

I'll let my machinist deal with it when I drop everything off for rebalancing. I just don't like surprises.