There where ever stereo tubed (valved) car radios?

[Electronic M]

MW or AM broadcast as it was known in the states did not support stereo until the mid-80's (unless countries outside the US developed some standard for it that I'm unaware of).

FM MPX stereo started in 1961, so there could have been car stereos that supported it...Probably only the luxury cars Cadillac, Lincoln, (Chrysler)Imperial would have had it.

There Was also simulcast stereo where a mono AM station would broadcast the left speaker signal and an FM station would broadcast the Right (though I may have the directions reversed)...That existed from some time in the mid-50's until MPX FM stereo replaced it. I doubt a car simulcast radio was ever offered by any company...You had to have 2 independent receiver circuits (1 for each band) that would double the power consumption, size of the radio and the tuning complexity.