The early catalytic converters are PCX stock numbers and late ones are PZX. Does anyone know if they will interchange?

 

You might want to call a Honda service dept and ask them if there's a tech note that says so. I can't imagine why they wouldn't though...

 

I just put an '06 cat in my '00 and it fits/works perfectly. I think the PZX part is less prone to the typical failure mode of the PCX part (honeycomb separates and breaks the O2 sensor).

 

Top: MY'05 Cat.
Bottom: MY'00 Cat.
The only change is the position of the Sec O2.
And it really is the only change: the M'05 cat I'm using now had a rattle from the the core and it also shifted = damaged the O2.
I guess no matter what year you use those cores will eventually start to rattle.
So far I was able to fix the core in place, it still rattles (a bit) but can't shift and damage the O2.