NS Train 905

I caught an inspection train this week, NS train 905:
NS 7578 leads train 905

 

Working front to back, here is the lead unit:
NS 7578 leads train 905

 

The second unit was an ex-Southern high hood SD40-2: NS 3294

 

Here is NS 34, built on as SD frame... NS 34

 

Another view of NS 34: NS 34 is on train 905

 

Bringing up the rear in NS 33: NS 33

 

That sure is a cool catch!

 

It was totally by luck that I caught it... I was especially excited about catching NS 34 on the ex-SD loco frame, as I have never seen anything like that

 

Umm... what is NS34? What does it do?

 

I believe that it checks the track's condition.