Diff is the same, just black. A lot of those tweak screw options can and have been done to the regular SupaStox. I still think the bumpier the track the better the previous design will work. The GT really is almost a full blown 12th with a full length chassis and no center shock. I like it. Note it is for GT racing only, but that is exactly what we are doing with it. Ease of setup looks to be seriously improved, but the previous one isn't hard to set up either. I think the huge difference is the front end with the variety of tuning upgrades. Ackerman is much improved with better adjustment all around. We really won't know if it's any better until the one Stan ordered on sight arrives.