My take is that SPC simply means it's too different from the original to pass off as the original. The 4003 SPC's (like the AC) have drifted a bit too much to pass as a 4003. The 4002 SPC very specifically addresses the fact that they didn't want it to be confused with a 4002 reissue or 4002V (if such thing existed). Weird? Nah, just acknowledging they are different than the original enough so it's not just a couple acronyms at the end of the model number like CB or VP.
My take is that SPC simply means it's too different from the original to pass off as the original. The 4003 SPC's (like the AC) have drifted a bit too much to pass as a 4003. The 4002 SPC very specifically addresses the fact that they didn't want it to be confused with a 4002 reissue or 4002V (if such thing existed). Weird? Nah, just acknowledging they are different than the original enough so it's not just a couple acronyms at the end of the model number like CB or VP.