I am fairly certain Primal Rage is, in fact, JAMMA(+). I had a PR cab that I tested other boards on and they all worked... with sound.
EDIT: I DO seem to remember it being in STEREO though... which means it may require an amp to get sound from... but I do remember plugging the harness in the cab in and getting sound from OTHER boards as well, but that doesn't mean it could have been wired for both JAMMA mono and JAMMA+ stereo though.