we have a 1936 cockshutt hart parr 28-44 serial number 507498 and it has cockshutt on the serial number tag. Cockshutt/hart parr on rad tank.  With oliver on block tag the rad could have been changed at some time on your tractor?  History of cockshutt book states early 30&#039;s as when cockshutt olivers were sold. There are no cockshutt records available.