I've got a DW-3000, great model - huge, tough and rare but not a G-Shock. The module does not have the rubber casing around it. It's circa 1985 so just after the G's came out. Has my favorite caseback design of any Casio.
About that seller - he's got a G-Shock case he's advertising as a DW-5000 but it's a 'JAPAN A' case style and the DW-5000 only came in 'B' and 'Y' so be advised if you're planning to bid on it.