'67 Barracuda bucket seat mounting

My '67 Barracuda has bucket seats, and I'd like to find some replacement hardware for them. Both seats are missing a stud on each. One thing I'm not clear on is if the seat tracks are supposed to bolt directly to the floor or if there's a spacer that goes in there. I've seen replacement bolt sets that have them and some that don't.

Prices are also all over the map for hardware. Any recommendations for a vendor with reasonable costs? Year One has the spacers and nuts (but not studs) for $24 for a single seat, and then I'm looking at another $15 per seat for studs via eBay. This isn't a concours restoration, so I'm not above using carriage bolts, washers, and nylocks to be cheap.

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