The cab is the same as a C10/20/30. Glove box insert is the same. I'm still waiting on a floor mat but got mine from brothers. Outside door handles I'm not 100% sure. Heater resistor I also go from brothers. Front fenders are unique to C50/C60 I'm not sure what else but a C10/20/30 will not fit. Wiring harness I believe can also be found on brothers also.
https://www.brotherstrucks.com/default.asp