Texas Miniatures use the following distinctive base markings on their miniatures. But note: it isn't clear if they modified the base markings on the various Heritage figures that they re-issued. The figures that originated from Texas Miniatures do have distinctive markings though.
Markings include the Texas Miniatures mark (a capitol T above a capitol M), the product code "4310", sculptor Richard Kerr's signature "R.Kerr", and a copyright symbol and the date "©1983".
Markings are hard to read but they include the Texas Miniatures mark and "R. Kerr sculpt".