Peter I think you sell the NRs short .
Earlier traction motor issues were actually pinion issues , not motors melting .
Aside from this I always though their adhesion issues were cause by their hardly hi tech bogie design .
I've told you of these times before .
Please explain how I got 1999 tonnes up Demondrille with one in admittedly good conditions , 1300 amps at 13 km/h down to about 8 over the top . Never missed a beat . Also got a bit more up Jerrawa with one in the dry .
One you wouldn't know about was the time we set sail out of Coot West one evening on PS6 . This one had part off a steel train attached out of Parks and weighed in at 4200 tonnes - a full load . As circumstances would have it the controller in Junee kept us going through Yass behind a wheatie , in the wet , that was leaking grain onto the rail heads .
Crawled up the Cullerin ranges as you'd imagine at 14-16 KM/H , never looked like slipping to a stand .
Unless things have changed full loads on the up south north of Junee were 1780 for Gs and 1840 for 81s , I think NRs were 2100 . I think you could easily substitute a pair of NRs on a wheatie that two 81s typically haul .
I think the best thing you could do was fit them with the later flexi curve bogies if suitable . I reckon that if you can get them to hold their feet you have a better chance of maintaining a speed at which the traction motors won't overheat .
Also , no spoke about it much but 81s didn't tend to survive too long tripping steel rakes out of Cringilla . Generally about a week or two and they would fry traction motors . They are good things but even the best can be beaten .