The HydraMatic transmission that was original-equipment in GMC trucks with the Pontiac V-8 had a large rectangular sheet metal side cover with the manual shift linkage going through it, along with a spring-loaded throttle position lever. It does not have a "Park" position at the top of the quadrant. The transmission used in the 56-up Pontiac, Cadillac, and Oldsmobile passenger cars was known as a "Controlled-Coupling Hydramatic". Depending on the specific carline, various names were used in advertising copy. This transmission had the shift quadrant which included a designated "Park" position above Neutral. The large sheet metal side cover was not present on that unit, and I believe it had an aluminum housing, not cast iron. It was not used in any truck application that I'm aware of.
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
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