The Dual range Hydra-Matic did not have a Park position on the shift quadrant- - - - -Reverse served as park when the engine was not running. It looks like you have a "Controlled Coupling" hydra-matic, which was erroneously called Jetaway by some people. I believe the last Dual range was installed in 1955 Olds and Pontiac cars. Chevy trucks never ran a controlled coupling transmission.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!