1050 was built from sometime in the mid '70's until the late '80s, when it was replaced by the 1060.  Both were available in 48.5, 54.5, and 60.5 feet of width.  The 1060 had marginally greater trash clearance, and used 47^o sweeps which is pretty well the industry standard, vs the 41^o on the earlier models.   The 1000 and 1010 were contemporary to the 1050, and the 960 was contemporary to the 1060.  The 1050 was essentially a 1000 with a second fold and associated strengthening.  The 1060 is pretty much a newer 1050, but the 960 went to over-center folding.  The early 1050s had shell bearings in the walking tandems, which were replaced by tapered roller bearings sometime around '82 or so.  The shell bearings don't last very long, especially on wide, heavier cultivators.  They are cheap because they do not have very much trash clearance (fore/aft), the shanks do not have very much tip pressure, and they are getting old.  I would expect almost any 1050 to need it's shanks replaced, because ours were shot and it was a pretty late model and we did not farm terrible amounts of acres when we used it.  The 1050 is basically a 3 row cultivator except for shanks moved to the front around the wheels.  The 1060 is maybe a 4 row...actually I think it's still a 3 but it has more shanks moved out around the wheels then the 1050 does.