Model identification help

[bodyman922]

I am in the process of purchasing a 1970 chevy medium duty truck. One fender has been replaced with the same color but different model. One fender reads C/40 and the other fender reads C/50. I am asking if anyone here knows the difference between a C/40-C/50? The truck has a 12ft flatbed on it. I have been told the rear axle has been changed, possibly to a 2 speed rear, kind of doesn't look like it came with the switch on the shifter but I'm not sure. The online VIN decoders don't tell me what model it is.

The model on the glovebox sticker says it is a CE41403.
The VIN starts with CE430P

I have seen other glovebox sticker pictures from C/50 trucks where the model is CE5... This leads me to believe it may be a C/40.

I can try adding pictures later if that is helpful.

Any help is appreciated.