Likely has been noted somewhere, but didn't find upon searching... I've noticed several otherwise stock in appearance ZHPs on the road with finned rear differential covers. Suspect that this is likely not a common upgrade as I never noted such an option on any of the ZHPs I looked at when searching. After mentioning this to a buddy, he reviewed the parts catalog - appears that cars equipped with automatics came with a different differential cover...has anyone noticed this difference?