Just to provide closure on this issue surrounding my non-functional fuel gauge...
I took the car to a local Mercedes Benz specialist shop. They were able to determine that the sending unit was fine, but that there was no power at the fuel gauge. They removed the instrument cluster and discovered that someone had previously been into that part of the car, apparently to service a SKREEM malfunction. During their "work" they "crushed" some sort of connector for the fuel gauge. The Mercedes shop was able to source the pieces they needed and it works great now. They had removed the steering wheel when they had the instrument cluster out. When the repositioned the wheel and started the car, the airbag warning light was on. Their SDS equipment would not communicate with the Crossfire's airbag module. They took it up the street to a Chrysler dealership that was able to clear that fault. The Chrysler guys charged $175 for their role in the solution. It probably took them awhile to find and dust off that equipment.