I would be looking at the condition of the fuel lines and rubber hoses. 89 still used rubber hose and steel lines. The fuel lines will start to weep where they are clamped to the frame, and the hoses will crack over time. Look for discoloration or witness trails, those leaks often will weep but not drip for a short while before they fail completely.
Another thing to look at is the condition of the hoses at the fuel filter.
There is also a joint on both the supply line and the return line up near the transmission. The steel lines are joined to braded steel lines as they go along the trans, those junction points will often start as a drip under pressure. Unfortunately, that area requires new lines.
On my 90, the leak at the transmission started the entire ball rolling. I ended up replacing all of both lines and all of the hoses and the filter. The newer Dakota's used the plastic lines, as much of a pain as it is to get the lines converted from the steel and rubber to the plastic lines, it was worth it in the end. Gene
