Loadstar, your comments regarding the Massey Harris model numbers has made me realise the 745 model tractors were from Great Britain, I had assumed they were from Canada.
A bit of research shows they were fitted with Perkins L4 diesel engines.
I had no idea Massey had a Perkins connection with that series of tractors. Here in North America they used the Continental diesel or gas engines. Not til the Ferguson alliance did they show up with a Perkins diesel option. Like this little model 50 from a 1958 ad. No more mention of Massey Harris from then on.