You can buy these new (repro) or at the very least, all the rebuild kits are cheap and very available. What year control valve do you have? They are very easy to rebuild but i would recommend a new one. Try ECKLER'S Chevrolet parts in Florida. Cheers. George.
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1957 Pontiac Pathfinder Deluxe sedan restored 261 six
1974 Chevrolet Caprice Estate wagon low mileage original 400 V-8