It's actually 8 instead of 4, but who's counting? Having rebuilt many Snapper differentials, both Xtra-Tough and standard, I couldn't see where the extra pinions made it any better, just different. Actually, when the first Xtra-Tough models came out, they were worse. They promoted the "Hardened steel bull gear". In actuality it caused the smaller gear to fail quickly. I think they quickly scrapped the hardened gear.