More to add:
My new mechanic said that he saw one other 300e 5 speed in Canada, tried to buy it, but it was sold already. He said that 5 or so were shipped to Canada. No way to prove that, though. He wondered if mine might have been a conversion. I don't think so, but I don't know.

On the car option tag by the rad, which code signifies a 5 speed?

My odometer and air conditioning work again!
Thanks,

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VR
1967 250SL