The knobs that I found years ago were either warped, cracked. or otherwise not usable.The plastic usually didn't last real long.
Does the reproduction have a rubber bushing in the center where it slips on the shift lever?I would consider painting one to matach my '39 color. ('39 was the same except for color).
Without the bushing it will act like an amplifier and you will hear transmission noises that you never know exisisted.
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Chevgene