Various embodiments of the invention are directed to a system for removably mounting a signal testing unit to a suitable vehicle surface, and optionally providing for an electrical connector to a power source, GPS antenna, and cellular antennas such that moving a signal testing unit from one vehicle to another can be accomplished more easily. The mounting system includes a connector plate that is attachable to a vehicle surface and includes a plurality of guide pins extending perpendicularly from the connector plate. Guide pin receivers are attached to at least two faces of a signal testing unit and, when each guide pin receiver slidably engages each of the guide pins, movement of the signal testing unit relative to the connector plate is prevented.