As with so many other early parts, there's a lot of confusion about original 901 shift knobs and reproductions. And, as with so many early parts, there are reproductions and there are reproductions. Some are earlier than others and very close to originals. Others are cheapies. Others are new very nice ones. I have found the main difference between all repros that I have seen and originals to usually be three things:

(1) The originals are noticeably thinner at the bottom than the repros and the edge is more rounded vs. the flat edges on the repros.

(2) The originals I have seen have been more of a matte black than a glossy black, but maybe that's due to patina.

(3) The originals had flattish numbers and most of the repro's have numbers that are somewhat rounded.

To further complicate things, a a fellow forum member has pointed out to me, the upper vertical part of the "5" was straight on knobs know to be original, but may be a bit slanted on knobs that could be reproductions or originals.

Here's one I believe to be an original:

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Here's one I know to be a later reproduction:

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I've seen knobs with thin bottoms, flat numbers and straight and slanted "5's". But I've never seen a repro without a fat bottom.

I hope that helps.

We need to cut a little slack sometimes because the differences between original parts and reproduction parts produced at different times can be very fine indeed.

JohnA