How wide was the cutter bar? Was it an auger feed model? The first two models that come to mind are the model 15 and the replacement for it the model 18. The 18 was a 7 foot cut auger feed machine and 1962 or 63 was the last of them. Production of those started in the 50's I am not sure of the year, 1954 comes to mind for some reason.  There were a few of them also built as Cockshutt models 18 combines. Questions/