Judd 1420 is an incongruous muling of an 1875 Trade-Dollar style obverse with a pre-1866 reverse from a Seated Liberty Dollar. Since the old reverse was not about to be revived, the only reason to produce this coin was to sell it to collectors (at a profit, of course) as a rare "pattern" issue. According to Adams-Woodin, the Mint struck six pieces, but that figure may be too low since six examples are known today (the odds that an entire mintage survived is possible, but low).
The finest certified example is the Simpson PCGS PR66CA. Possible "raw" contenders for the crown are the Bass Foundation and the former Eliasberg examples.