IMHO you could buy it, get it driveable and flip it with at least a thousand profit.
What it's actually worth depends only on the market and those Cummins trucks are in demand. Everyone "knows" the engines are good for half a million miles, whether that's true or not.

My '93Suburban has 253,000 miles and it isn't worn out yet, although the seal in the front of the transmission is.

But for a grand it's a no-brainer.

R.