First off there are no 28MM 300ZX calipers there are 28MM Q45 calipers which is another option. For the 300ZX the 26mm came in aluminum only in 1990. That is it There is no other year 26mm calipers were made. The rest of the calipers are 30mm and depending on year are aluminum or iron. Also if you use the Goodridge SS lines you don't have to get conversion lines for the front. The Goodridge lines have a shorter banjo bolt than stock lines and fit perfectly. I found this out a couple years ago and have had no problems with the setups I have done...