When Chevy released its third-generation C/K pickup truck, the stout and sturdy performer captured the attention of Chevy and GMC truck enthusiasts, and as a result, millions were sold over its 18-year production run. Because the truck featured a new cab design as well as rounded windshield corners, rounded cab roof, and sloped and rounded doors, they were nicknamed the "rounded-line" trucks. Although the older Chevy/GMC pickups are more exclusive, the third-generation pickups are plentiful, are increasing in collector value, and fortunately, parts are readily available.

As an on- and...