Serpentine belt differences?

[ronwest]

I'm replacing my radiator, thermostat and hoses (preventative maintenance) and while I'm doing that I'll replace the serpentine drive belt as well.

My local Ford does not have a belt in stock but I can get a Dayco belt locally from a gasket/belt supplier.

According to the supplier the Dayco cattledog lists belts "AU 98-02" and "AU XR6".

I'm guessing that the 'XR6' means VCT and the other is for non-VCTs?

Can someone confirm that VCT/nonVCT belts are different as he doesn't have the "XR6" one in stock and I'll save myself a trip.