Bob, the previous post is correct in the carb ID numbers. We tend to make this too difficult because many listings are shown as "with smog pump" or "without smog pump" or "with IMCO" or "without IMCO". In truth I think that ALL 289 and 302 cars in 68 with automatic transmission were equipped with IMCO, and all 4 speed 289 or 302 68 Mustangs were sold with a smog pump. Also the GT 350 Shelbys were equipped with the AUTOLITE 4 BBL carbs in 68 until early Spring (Feb or March) and then Holley was used thereafter. A recall was then put in effect and all of the early Shelbys with the 43oo Autolite carbs were changed to a Holley, a different Holley application for an automatic or a standard transmission. The 4300 series used on the 302 4 BBL cars was less then expected and many were tossed because they just simply would not work well. The ordinary Mustang owner in 68 who had a small block with a 4300 four bbl was not so lucky as to be included in the recall and had to suffer with the problems associated with the 4300.