Which model of the Cessna 172 was introduced first with the Lycoming engine?

The Cessna 172 A model was the first variant of the Cessna 172 series to be equipped with a Lycoming engine, defining a significant shift in the aircraft's powerplant. Prior to the A model, earlier variants utilized Continental engines. By introducing the Lycoming engine in the 172 A, Cessna aimed to enhance the aircraft's performance, reliability, and maintenance characteristics.

The subsequent models mentioned, such as the D, N, and R variants, followed later in the series and continued to build on the technological advancements and improvements established in the Cessna 172 A, but the A model specifically marked the introduction of the Lycoming engine to the 172 lineup. This transition was a key milestone in the evolution of the Cessna 172.