Off the top of my head 69 and 73 ran for two weeks on the gypsum traffic in 1985 
as a trial.
Despite the crap recently published in the same magazine in which I had a long 
letter published and a book by an "expert" there still seems to be a gross lack 
of understanding re the NT's.
 For the last time, I hope, three NTs 69, 73, and 74, worked port lincoln until 
late 1989.They were cut up (74 went first in October 1989 after she broke her 
crank July 30 1987;nearly ten years ago!) and 69 and 73 got the chop in August 
1990. They had worked their last shunts 10/6/88 and 21/9/88 respectively..
The other NTs were scrapped at Port augusta, though I have a feeling 67 was cut 
up insitu at Gladstone.
Thus, they were not all transfered to Plo as apparently implied in a recent 
modelling magazine, nor are they "in store" as per a recent book and Oz 
locomotives.
Regards
Nic