The late 02's -06 have a 2pc header style exhaust manifold & Y-pipe with a pair of mini converters and a pair of updraft O2 sensors. Three cylinders per mini cat, and sensor. So there are 3 converters on an 02-06
Pic
http://i.ebayimg.com/t/2001-2003-Jeep-Wrangler-TJ-4-0L-Front-Exhaust-Head-Pipe-/00/$(KGrHqEOKi8E3K2jvGugBN-Lw)Yos!~~0_35.JPG