I used to have an 18-28 Cockshutt Hart Parr.  The serial number tag on it said very clearly--Cockshutt across the top of the tag.  At the bottom of the tag it said&amp;quot;built by the Oliver Corp.&amp;quot; or something to that effect.  The radiator had Cockshutt in large letters, with Hart Parr in smaller letters below.  The block still had Hart Parr cast into the side.  It sounds to me like the 28-44 could either be original, or a hart parr that has had the radiator changed.  As we all know, anything can happen over a period of around 70 years.  Terry.