I finally remembered to check the trucks in my yard before dark today.
'53 Chevy yard dog, 3/16" stripe about 3/16" above cab joint.
'50 Chevy half ton, 5/32" stripe about same position.
'51 GMC 2-ton, 5/32" stripe about same position.
'47 Chevy 2-ton, 3/16" stripe about same position.
Greg Hill sent me pics of his '54 Chevy half ton, 1/4" stripe about same position.
'54 GMC did not have a stripe.
Organ builder's '53 Chevy and the '49 GMC Huck linked to seem to be consistent with these.
I'm thinking the position was set by the book for all AD/ND years that had the stripe. The width varied with the striper.