Adding Headrests to Early Bucket Seats

Never actually done it. Was trying to find replacement hardware once for an old seat. Hard to find so I started looking at different alternatives. I would say pick your headrest first, buy applicable sleeves and measure twice. Especially if your seats are nice and/or hard to replace...............
Honestly, once you butcher them up with headrests, they aren't factory anymore so I would just buy safer seats to begin with.