What years were those Massy heads built.
When they changed models did they add a number in front of the 44, and 63 with a model change?
IH started the number system in 64 or so with the 200 series. ex- 224 243 244 233 and so on. They went to the 700 series 1968 to 70 somewhere in there. The 800 series came out in 75 or so.