Which Ford model built from 1928 to 1931 was a common early hot-rod base?

The Ford model built from 1928 to 1931 that became a common early hot-rod base was the Ford Model A.

The Model A replaced Ford’s long-running Model T and offered a sturdier, more conventional platform for modification. Its 201-cubic-inch, four-cylinder engine, three-speed transmission, broad body range, and straightforward chassis made it practical for builders working with limited budgets and ordinary workshop tools.

Hot rodders particularly valued Model A roadsters and coupes. Removing fenders, bumpers, tops, and other weight helped improve performance, while later builders often added more powerful engines, altered suspension components, and changed wheels and tires. The 1931 roadster became especially attractive because of its open cockpit and relatively light construction.

The date range in the question refers to the Model A versions commonly used by early hot rodders, not the complete production span of the generation. Ford produced the Model A from October 1927 until March 1932, selling it as model years 1928 through 1932. The Model B followed, while the Model T was its predecessor.