1966 Barracuda

"A 273" is stamped on the driver front side of the block below the head indicates the engine was for a 1965 model year car. If the stamping is "B 273" then it's for a 1966 year car.

Look closely and you will also find the engine assembly date located below the "A or B 273" stamping. Month and date only, no year. (example 11 23 = November 23 ) This date usually precedes the car build date and in this case a 1966 car has an engine built in 1965.

Block casting dates don't necessarily coincide with model year as mentioned in the above posting.