You do have a piece designed by Spratling but was made some time between 1978 and the last few years. 1978 being the year that the Mexican government began issuing the T marks to silver makers. The S stands for Spratling and the 24 stands for the 24th silvermaker to apply for the T mark. After Spratlings death in 1967 the Spratling ranch continued to produce pieces using the eagle hallmark for a very short period of time. In 1968 the Spratling ranch was sold to Alberto Ulrich. By all accounts the production of Spratling silver was discontinued at that time. At some point around 1978 Mr. Ulrich began to produce Spratling designs once again as he owned the rights to do so, but by this point he was required to use only the TS-24 mark along with the Spratling hallmark. Hope this clears things up for you.