If you know someone who can weld and is handy you can actually make one pretty easy. Back before reproductions were readily available my friend needed one for his ‘67 Mustang. I had another friend of ours fabricate one using the shaft of his core C6 as the basis, cutting off the arm it had and welding on a copy of the ‘66-‘69 floor shift arm, using one of mine as a pattern. It’s a pretty basic design, and you don’t even have to replicate the bend it has in it if the arm you’re starting with already has the bend. Just be sure to start with a shaft that has the two slots in it that engage the neutral safety switch. When he was done it was pretty hard to tell the difference. Just throwing it out there, if you decide to go that route and need a pattern I’m sure one of us could trace you out one on a piece of paper.