The vacuum actuated control valve on my ‘55 Thunderbird seems to have a coolant leak. At first I thought the threads in the Blue Thunder intake manifold were at fault but after speaking to John Mummert he suggested that the valve itself was at fault. My question is this: which is the smarter move - purchase another new outsourced after-market manufactured valve (which is what is presently leaking) or purchase a NOS valve on EBay ( which may have a compromised 50 year old internal rubber flap)? Anyone have any experience with the NOS valve??