Mickey O

Here are four 50's GM cars that came with buckets, '58 Bonneville, '59 Bonneville, '59 Buick and the '58 Buick Wells Fargo show car (might be the first non-corvette GM to have buckets that wasn't a prototype, also has power vent window and fiberglass boot, also probably the first GM car to come with real guns). You could also get bucket seats in the '59 Cadillac.

https://www.streetmusclemag.com/news/the-legend-of-the-fbi-buick-grand-nationals/