The base part number is ISM420R1-C33. The ROM Code part number can be read from the GPS in OSP (Sirf Binary) mode only and the version is :  “GS4e -4.1.2-P1”.

The GPS will initially come up in OSP at 115200 baud, unless you change it with the strapping pins 4 and pin 5 or have a SPI or EEPROM attached and then unit will start in NMEA 4800.