here are a couple things the check. this is kind of general, not exact
1. the steering rod from the gear box on a C goes to an arm under the radiator. the rod on the B goes to the left wheel king pin area.
2. the steering arm on the gear box of a C points straight up, the arm on the B points straight down.
3. The rear wheel hub on a C bolts to the axle with a 5 bolt pattern, the B hub usually has a splined center with one BIG nut in the center.
4. The rear axles on a C are about 6 inches wider on each side than the B. Generally the C wheel hub spacing is about 72 inches while the B is about 60 inches ( i think).
there are exceptions to the rule, but this gives you a general idea of what you got.