There's no official record of the exact number of 1968 Dodge Coronet R/T's (note the correct designation is R/T, not "R") with 440 Commando engines produced, nor is there a way to accurately determine how many are still on the road. Dodge didn't keep detailed production figures broken down to that level of specification (engine size and specific options package).
While some enthusiasts meticulously track these cars, compiling data from surviving documentation like build sheets, the information is incomplete and scattered. Therefore, any number given would be an estimate, and probably a broad one at that. The number surviving is even less certain; many were scrapped or destroyed over the decades.