There are some people in the business of replacing the electronics in these old radios with a new solid state board. They use the mechanical tuning system and the oscillator tuning coil. I am not sure if it is an FM only conversion.
Well, that's essentially what I did after the same frustration. Only instead used a basic '60's solid state radio chassis for my basis.
Nope, no FM but it's only a noisy '50's truck so who can really appreciate the full effect of FM and stereo anyway?
Besides I'm confident there are inexpensive attachments somewhere out there that can be fitted to this unit for FM, etc. -- the 1970's had them.
Btw, here's an alternative you may ultimately be referring to.
It would then be fully up-to-date:
http://www.tech-retro.com/Aurora_Design/FMR_images.html..although a friendly local auto stereo (repair) shop may have to supply the PO for you if they don't have the where-with-all to do it themselves.
