Ok..what Is It?

[Tony Smith]

The number C11Q-19802 B is for the case casting, not the whole T/C assembly. There was a later casting with the part number C29Q-19802 S which featured a larger oil sump, similar to the Chev case I've pictured above.
The complete Ford and Chev cases, either in the case of 15cwt single speed transfer cases or the two-speed cases, will physically swap between Ford and Chev. All mounting points, controls and driveshafts are in the same locations. There are some complications in putting a Chev 2-speed Case into a Ford as the Ford 2-speed case has it's shifter mounted on a bracket bolted to the side of the case. The Chev 2-speed has it's shifter on a bracket on a chassis crossmember. Internally, the gears, shafts, bearings, shims and gaskets SEEM to be interchangable as the parts books list both Ford and Chev numbers for the same parts, however I have never dissambled a case and reassembled it with parts from another case, so I can't say for sure.