I think its a Molex MLX series. However, if you are going to go through that much effort, why not just source one of the number of weather-seal type connectors and pins. You just need one thats got the correct number or more, of cavities.

For whats its worth, that connector is there so it only takes the builder putting in the stereo head, 2 seconds to plug it up, rather then 20 minutes to splice and heat shrink the wire ends. Honestly, it serves no other purpose. The conventional think is, once in stalled, theres no need for frequent removal, so the connector is not for that. Any replacement down the road, will not have this connector........