Blue is 1954 (Z-3) and Red is 1958 (D-2). The 54 Super Speed (Z-3 & 4) was only sold in the Blue TV Special case for the last 6 months of 1954 (production ended). Also in 1954 the (1950's style) Flare Tip Super Speed model was introduced. The (Blue) cased set is very hard to find and somewhat rare.
