I have discovered the Browning Hi-Power. Need some help figuring out what model I have. So far, I've been told that the NM in the serial number means it was manufactured in 1990. Does that mean it is a MKIII? Need to know because I am in the process of ordering some parts and night sights and need to know if it is a MKII or MKIII. Any help will be greatly appreciated. Any customization hints from folks familiar with this sidearm will also be well received.