Basically, the differences between a regular 273 (2bbl) and a 273 Commando (Plymouth's name) and a 273 Charger (Dodge's name) are: Hi-comp pistons (10.5:1), a bit hotter camshaft, the iron 4bbl intake with Carter 500cfm AFB 4bbl carb, dual-point distributor, fancy valve covers, and chrome air...