Great video! These things will have been pushing 40 years old when this was filmed, and some of them look very work worn, but still plying the routes and getting the job done. I know the 31s get a bit of stick for one reason or another (underpowered seems to be the common one) but NR were still using them on test trains up until fairly recently, some 60 odd years after they were built, and that certainly says something.

Great locomotives. Considering they were powered by a de-rated version of the class 37’s engine and many of those 37’s are still running now, there must have been a large number of very usable power plants made useless when the 31’s were scrapped.