D types were the best. Look at this:
The D types were my all-time favorite
10 car 60' train: 20 trucks
9 car 67' train: 18 trucks
8 car 75' train: 16 trucks
4 unit 150' articulated train (3 50 foot segments per unit): 16 trucks
Train dude: Wouldn't it be cheaper to run a train of articulated trains? (less maintenence due to shared parts, much like R-44/46.)
The D types were too heavy to be practicalthe axle load of articulated trainsets is also higher meaning the roadbed and rails take a greater beating.
And Train Dude, Could you get the MDBF for an R-32's when they were about 13-14? It would be cool to see them matched up against today's R-68's.
Actually in the 70s, the r-32s ran well, relative to the rest of the fleet. But in those days 15 - 20,000 was a high MDBF so draw your own conclusions. Remember, that was the era of deferred maintenance.