1. A tillage implement adapted to be connected to a tractive vehicle having spaced ground-engaging wheels and first and second implement support links at the rearward end thereof, said implement comprising: a frame having a forward end and a rearward end; a plurality of ground-working tools mounted on said frame between said forward end and said rearward end; a steerable tail wheel movably mounted at the rearward end of said frame; linkage means connected to said tail wheel for controlling movement thereof; and hitch means connected to the forward end of said frame, said hitch means including a crossbar having spaced support means for connection to the first and second implement support links, a generally upright steering tube means mounted upon said frame, a steering post within said tube means and connected to said linkage means and to said crossbar, first means for adjusting said steering tube means relative to said crossbar to position said steering tube means at one of a plurality of selectable positions, means on said frame defining a laterally extending groove, means associated with said tube means slidably received in said groove for providing a second universal adjustment means for varying the location of said tube means relative to said frame, and means for securing said tube means at a selected position along said groove, whereby the first ground-working tool carried by said frame can be accurately aligned with the outermost wheel of said tractive vehicle.