My 5.3 has one on each bank and one more after the wye. I gutted that third one cause the 3rd cat has no sensors. Not sure if the 4.3 is the same, but can confirm the 5.3 has 3 cats. Pretty evident if you crawl under and take a peak.
A forum community dedicated to Chevrolet Silverado and GMC Sierra pickup owners and enthusiasts. Come join the discussion about performance, modifications, classifieds, troubleshooting, maintenance, and more!