I'm hoping that someone on here has found a place that can rebuild a 12V radiator or blower motor. Perhaps not for your shelby but maybe for another of your cars. Replacing them with a chinese repro is not possible for those of us with low-volume "furren" cars with odd-ball mounting brackets and cases. Anyone with an old brit car knows what I mean. Thanks.
Culver Electric in Sacramento, CA is not automotive but has been rebuilding all kinds of electric motors for about 70 years. May be worth a call based on other responses. Ask for David.
Check for vendor listings in Hemmings Motor News under "services".
I checked a couple of days back, four are listed.