It's a 24 valve automatic transmission, so they aren't good?
It's not that the 24v automatic are not good, it's just not quite as desirable as the simple 12v...
One of my trucks is a 2002 24v with a 6 spd, and engine wise, to date I have only had to put one injector pump, and the truck currently has over 200k.
The 1998 Automatic should be a 47re. When it goes out, spend the coin on a built transmission. Not one from the local transmission shop, plan on spending a few grand, and have one built that will hold up for the long haul.