When was the year of the first Colt duo tone with both 22lr and 22mag cylinders?

The first Colt Duo Tone revolver that featured both .22 LR and .22 Mag cylinders was introduced in 1970. This model, known as the Colt Diamondback, allowed users to easily switch between the two calibers, enhancing its versatility for shooting enthusiasts. The Duo Tone finish added a distinctive aesthetic appeal to the revolver.