1875/6-Go NGC AU Det Mexico Silver 8 Reales Very Rare Overdate Coin (20092403C)Almost Uncirculated Mexico silver 8 reales coin. Minted at Guanajuato Mint (Go mintmark). Very Rare overdate variety with 1875 6. Certified by NGC to AU Details (Rev Scratched). Dark toned with underlying luster. Dunigan Go55: "The normal date is common, while the overdates are very rare." A reverse year (1875 6) overdate is very unusual. Dunigan gives a plausible explanation: "Perhaps at the end of 1875 there was an unexpected demand for more coinage