my 2002 4.7 4x4 needs new cats

After replacing the o2 sensors it still has a cat deficiency code

I am guessing the whole y pipe has to be replaced since it is a California truck. Could I just weld in new cats?

anyone done this before and have a source to buy the parts?

 

I think you can weld them in, you could get some magnaflow cats and put them on. Does the 2002 have the 2 minicats, 1 for each cylinder bank or just 1 cat?

 

It has 3 total cats there are one on each side of y pipe right near each exhaust manifold and one after the y pipe merges into one pipe. I want to just weld new ones in.