[davepl]

Because the manual trans versions of these trucks that I've owned have been, well, unloved.

I had a four speed on the floor which wasn't bad, but it was really a 3 speed plus a "bull low" for pulling your boat out.

I had a three speed on the tree which worked well, but it was a 3 speed on the tree.

Those trucks often wind up converted (though the 4-on-floor would be nice converted to a better manual). So that's why I think they're harder to find.

Odds are the manual trans trucks lived a harder life. Consider my auto trans truck, which was a camper, which didn't even have rusty shackle bolts. Very different life from the 3-on-the-tree landscaper truck.