RE: Genesis is the one
It's a JR Racing DZ8550 Ultra Torgue steering servo.
I bought the 4 wheel steer kit because I had read how bad the turning radius was - plus I'm running Jumbo Kongs.... This servo has mad me decide to not add the rear steering kit - even with Jumbo Kongs this thing turns tighter than my big block Maxx....
Hope that helps!