It's not easy to find in the service or owners manual.
But here it is, bottom right of page.
"Connect battery ground strap to battery negative post."
http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm1223.htm

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-