You *can* find them at the JY. However, I think they are probably rarer than GM 60s if anything. Not as in more desireable, just harder to find because less were made. Also , everyone and their brother knows to look under a K30 to get a d60, but hardly anyone knows to look under a late 70's 3/4 ton dodge with the snowplow package.
[brag] The funny thing is, I bought a dodge 60 from a junkyard for $150. [/brag].
It was buried in junk and had been for a long time (really rusty, some moss, etc). It had a companion rear d60 that had "1978 dodge w200" written on it. When I decoded the BOM, it came up as a dodge 600/700, which i think is an error for a couple reasons...dodge medium trucks didnt use an 8 lug pattern like the pickups, and i'm guessing the medium trucks didnt come in fulltime 4wd models (my axle has external drive flanges). so i actually think whoever wrote that on the rear d60 however long ago was right. anyway, the only locking hubs available for this axle are MM classic hubs, which I haven't really heard good things about. I can convert to GM SRW outers, but parts are $$$ and all the dually guys want to do this too, so I probably coulnt find used parts for cheap. Also the axle has neckdown shafts which are weak, but there are newer shafts that are a direct replacement. Other than that, (and the size differences mentioned above), they are the same.