I had one in my 1966 GT350 and now finishing new Cobra had one to put in but ended up selling it as it was too tight for me. The Kirkey seat came with the car I bought and was a 16. They come in 15, 16, 17 and 18 and although the 16 probably would of been ok if I was racing all the time I really needed a 17 for driving on the street. The measurement is across your bottom and was told by Kirkey to sit on the floor with your side facing a wall and put a 2X4 on your other side and measure the distance. My measurement was 17. Cool seat and they really hold you in....
http://kirkeyracing.com/index.php?li...code=Series41V