I recently heard somewhere (can't remember where) that you could get a non-porthole hart top if you wanted it in 1957. I don't have any proof of that. Just something I heard.
I heard that they could be deleted in 56 and 57. If so, you got an emblem at about the same spot the 55 top had it. Different emblem for 57, I think 56 was the same as 55. I added the “dealer option” portholes to my 55, blind as hell without them. But this is more urban legend information than the real stuff. CTCI info probably has it right.
Porthole window hardtops were optional in '56 & '57, but they were popular and more were ordered than the non-porthole tops.
'55 and '57 non-porthole tops had year specific emblems. (photos below)
'55 = Ford Crest. '57 = round T-Bird emblem, '56 non-porthole tops had no emblem.
It has been a long time but I remember hearing that port hole or not was a no cost option. I have had '57's both with and without the port hole tops. You really need the port holes for visibility.
I cannot say for sure but I do know the tops will fit all three years the only difference is the rear clamps and clamping plates. As far as I know you could get a hard top and after mid1956 you had to specify whether porthole or non-port hole. Porthole tops were not available before mid 1956.
I'm attaching a sample price sheet from one of my books.
I have a non porthole 57 top. It came with my 55 bird. I had it since 1967, when I bought the car. At the time I didn't know the difference. Later on, after doing different kinds of work to it I figured it out. sanding it revealed (among other things) that it had at one time the round tbird medallion on it originally.
They existed. My mom bought a '57 T-bird new with no portholes. She had a choice of several but she wanted that car because it had a 312, 3-speed manual with an overdrive. I inherited it and eventually and sold the car to a collector who was looking for a port hole delete car. When I told people I had a '57 T-bird they would always say, "that's the ones with the portholes". Then I had to say, "all of them except mine". They have a little round emblem on each side of the top that the porthole cars do not have.
They existed. My mom bought a '57 T-bird new with no portholes. She had a choice of several but she wanted that car because it had a 312, 3-speed manual with an overdrive. I inherited it and eventually and sold the car to a collector who was looking for a port hole delete car. Really nice original paint car. When I told people I had a '57 T-bird they would always say, "that's the ones with the portholes". Then I had to say, "all of them except mine".