[AT] 3 point sickle bar

[Len Rugen]

There were several different setups for 3t mowers.  The chains MAY hook 
to the toplink at the tractor to limit how far the mower drops.  They or 
the bar may connect somehow to lift the outer end of the bar when the 3 
pt. is raised.  You need to figure out what you've got before we can help. 

My JD 350 has a lever that connects to a plate bolted to the drawbar to 
lift the mower.  A sickle bar usually doesn't just rest on the ground, 
even when "down" much of it's weight is carried by the tractor so the 
bar can float with less drag.  Without that float, little tractors can't 
handle the side draft and it turns into a harrow on the gopher mounds.

Is it a pitman or balanced head mower?  Can you take pictures?