Found out that '03+ 4.8L trucks have a male square end on the sensor side and '03+ 5.3L trucks have a female square end on the sensor side! The thing that sux, Autozone has the O2's for the 4.8L at $120 each and the O2's for the 5.3L at only $45 each. Same sensor, different sex! That sux for us 4.8L owners.

So what I did was use the plugs off the old O2's on the new O2's. Just had to make sure the letters matched on the plugs, A-A, B-B, C-C, D-D.

 

beautiful thing! Expensive connector eh?