[Gmecm] Going from 1-wire to heated O2 sensor

[Denny]

According to www.rockauto.com the AFS20,21,76 are all listed for the 5.7 
truck  . It list the AFS21 for the van! It looks like 20 and 21 are single 
wire(non-heated) and have the same connector but the 76 is multi wire 
(heated)