Originally Posted by JP@AK

Here is some additional information about the Model 65-1 for you.

The Model 65-1 was the first version of the Model 65, introduced in 1972. It was a new model line, based on a special order by the Oklahoma Highway Patrol for the Model 64-1 upgraded to chamber the .357 Magnum cartridge in 1972. Later that year, the designation was changed to Model 65-1. The -1 variant was replaced by the 65-3, in 1977.