Original (Black) vs. Stanadyne Gray Connectors
The socket on the original Stanadyne PMD/FSD module is keyed so that the connector cannot be inserted backwards. The aftermarket PMD/FSD modules are keyed the same way.
Stanadyne developed their own "improved" version, manufactured in a gray housing. They changed the way the socket is keyed, and provided a new harness to be installed on the engine. This new key design is deliberately incompatible with the original.
The picture above shows the original (black) connector on the left, and the Stanadyne Gray connector on the right.
When ordering an extension cable, you should select the one that matches the PMD/FSD module you will be using. All of the modules we sell use the original connector. All of the extension cables we sell will connect to either the original or the "gray" harness on the vehicle.