how many catalytic converters are there on a 05 4runner v8

It would be more helpful to adress that question to the mechanic that did the actual testing.

as pushrod stated,and you could copy and paste each link and get an idea of how many converters (with or without exhaust manifold),left and right,upstream/downstream 02 Sensors and compare prices from each place,big difference in prices. https://www.rockauto.com/en/catalog/toyota,2005,4runner,4.7l +v8,1430997,exhaust+&+emission,catalytic+converter,5808 https://www.rockauto.com/en/catalog/toyota,2005,4runner,4.7l +v8,1430997,exhaust+&+emission,oxygen+(o2)+sensor,5132 https://www.autozone.com/emission-control-and-exhaust/catalytic-converter https://www.autozone.com/emission-control-and-exhaust/oxygen-sensor