The last year you could get bucket seats from the factory was, I think, 1975 in the Torino Sport models. These would also be the same models with the rare and elusive floor-shifter and console. Bucket seats might have been used more frequently in Rancheros, and seats from '77-'79 LTD-II's and Cougars would work as well.
Do you have a standard bench or the split bench with armrests? If you're just looking to replace the standard bench seat, you might be happy with the split-bench; they're a heck of a lot easier to find than buckets.
Here's an interesting set on ebay:
eBay Motors: 1973 1974 1975 Ford Ranchero Torino Bucket Bench Seat (item 200219068260 end time May-24-08 19:32:20 PDT)