The SMPVs from the 1987 pilot-year did not use a whip antenna on the 1/4 panel, which you can tell was removed from E408383 when the CHP converted it from a B&W into a SMPV:
At least some of the ones from the 1989/1990 era did not have a whip on the 1/4 panel:
...but the ones that followed did have a whip antenna on the 1/4 panel, like this car as seen on page 1 of this thread:
As Michael/mac88chp said, the latter year SMPVs were configured closer to regular B&W units than the previous years. But they are still very cool CHP Mustangs!