It might be the 1747-CP3 that you need the pinout for, but it also might not...
Depending on which port on the SLC 5/03 are you talking about connecting to, which protocol, and whether or not your computer has a serial port can all have a bearing on which cable, cable and serial adapter, or cable and interface converter you might be going to use.
The 1747-CP3, or any RS-232 9-pin to 9-pin null modem cable, is probably the most used to connect to the SLC 5/03 on Channel 0, and is probably what you are referring to, but you could also be using a 1747-UIC with a 1747-C13 RS-485 RJ-45 to RJ-45 cable to connect to Channel 1, which is fixed for the DH-485 Protocol.
Also, if the SLC is already connected to a 1761-NET-AIC then you could even be using a 1761-CBL-PM02 RS-232 9-pin to 8-pin mini-Din cable between your computer and the AIC.
As I said, it is probably just the 1747-CP3 you need the pinout for, but if you could confirm your intended physical download route to the processor then I/we can be sure you're getting the correct information you need.
Regards,
George