Agreed. What this transmission really is, is a heavy duty 4 speed overdrive, as 1st gear is hardly ever used. It's durable though and should stand up to a heavy vehicle with a reasonable amount of power.
$23/qt, on amazon, but with kind of a ridiculous lead time, which seems suspicious. Last time I needed some I just bought it at the local dealer for the same price... but that was around oh, 14 years ago. Some places I've found it listed say it's discontinued. I haven't looked further into it just yet but now that I own another truck with the NV4500 it must be time to dig deeper.
Richard