Here's some added info from another 1955 GMC Sales resource pamphlet that lists the engines and models info (scroll down to page 15 of the pamphlet for engine info and page 17 for electrical info):

GMC Trucks New Models and Features for 1955
Attachments

~ Dan
1951 Chevy 3 window 3100
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"My Grandpa Carl's Truck and How it Became Mine"
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