I quick web peek indicates most wheel cylinders are going to run around $85 and up for resleeving from the few companies still offering the service. Another check of sources shows Rock Auto is currently offering
Raybestos WC15315 Wheel Cylinders at $47.79 each + shipping.
Phil - With this availability, I think you don't need to try and find another manufacturer unless you know of some issue the Raybestos parts???
I also agree with Jerry (HRL) about saving the old ones. You never know when you may want to see about restoring original pieces or offering them to another Bolter looking for original equipment parts.
