The upgrade model was the Cutlass, which all had 4 bbl carbs and all were 2 door coupes (post) or soft top (convertibles).
The Jetfire was the last model offered, having the high compression V-8 with the turbo. The Jetfire was built on the convertible chassis with Buick Skylark "true" hard tops (NO POST) welded on. They were the ONLY post-less hard tops in the complete F-85 line up.
All plain Jane offerings were 30xx and all upgrade offerings were 31xx.
