Old farm tractor driven sprayer pump w/PTO coupling Delavan

Old tractor driven roller type sprayer pump from an old farm estate. This pump is made by "Delavan - West Des Moines, Iowa". It has a splined coupling to connecting to the PTO (Power Take Off) shaft of a tractor. It measures about 6.5" across and 5" long on the pump ( 8.5" long over the PTO coupling). It has 1" OD (outside diameter) threaded brass nipples threaded into the ports on the pump.

The drive spline measures about 1 3/8" across (measured over the spline teeth on the inside of the coupling) and has 6 teeth.

This pump seems in good condition, although we haven't run it (just turned the pump over by hand).