Leaking from drive line area?

[9 LIVES]

my 98 2wd 5 speed 12 valve is spraying some oil all over the underside of the truck. The pattern is of something that rotates due to the 8" width path of oil splattered under the body all the way from 1 frame rail to the other. It is a mild brown color just a tad darker than fresh motor oil. The drive shaft where it slips into the back of the tranny is dirty but not oily. And the back of the tranny is dirty from road dirt and grease but no oil?? :bang

Anyone have ideas as to what to look at?

 

[joefarmer]

Fuel tank? Rusted fuel lines?

 

[9 LIVES]

Doesn't smell like diesel... But I did check that

Whatever is leaking looks like its spinning while its leaking. It has sprayed a sheet of oil from one frame rail to the other and about 8" wide path. Maybe I can take some photos tomorrow