No, the "among other things" includes the leafspring perches being spaced wider, and the driveshaft flange is smaller. Also the brakes are probably smaller.
Ranger axles are not at all rare, I would look for another one at a wrecking yard. Anything from '93-forward will be a direct swap on your '99
I'm hearing that only the 98-2000 7.5 are direct swaps. What is the difference from 97 to 98? I have found a 1997. I have not found a 98-2000 yet.