The large ones were up to mid 77. The smaller ones were in response to the upcoming convertible models. The way the conv top mounts to the rear panel, the larger gas cap and opening would have been partially under the top, thus the need for the smaller cap. You guys have it backwards. The large ones are easy to come by. The smaller ones routinely trade hands for $50 plus. Reason being, most of the early coupes have all ready been scraped or turned into parts cars. Low demand high supply. The opposite is true for the smaller ones. Almost all TR8s and all of the TR7 verts used them. Those are the cars that are more likely to be maintained and still driven. Gas caps are lost when people fill up their car and leave them behind. I have several of the large ones if you need one. Even have a factory locking one with the BL swirl that came on one of my early TR8 coupes.