I recently found a couple ads on Guns America that listed a Marlin 1893 and another was for a 1894. Both had screws plugging holes in the receiver tops. I was surprised as I wasn't aware that any Marlins of this early vintage were factory D&Td for sights or mounts, yet these appeared to have been done at the factory. There were two holes on each gun and the hole spacing looked to be the same and in the same location on both rifles. What type of sight or mount would have been used if indeed the holes were meant for that?