I put the #5464 in the search box, it came back with the plug listing, then I clicked on the link to see what vehicles the plug would fit and the Rincon was listed at the very bottom of the list.
I just went back to the NGK site and started from scratch looking for the plug that fit a Rincon, and it lists the 5464 number. The number IFR5L-11 doesn't show that it fits anything, its listed on their site but does not have an application that it fits.
Very strange. They also don't show a listing for a 2004 Rincon just 2003.
Edit to add:
If you go to their site and click on sparkplug 411, you should be able to find the differences betwwen the two plugs, I didn't do that yet, might have to later.
Is the #5464 an advanced auto parts stock # or an NGK stock #? I went to ngk's site and found the listing for both the 03 and 04 rincon. The plug listed is the IFR5L-11, stock# 6994. I had advanced auto order me the #5464, should be here tomorrow but I'm getting the feeling that it's not going to be the right plug. The girl at advance told me that the #5464 did not cross reference to anything. This is all before I found this latest #6994 info.
Talked to tech sevice at ngk and the guy I talked to said that the#6994 was a misprint and the right number was #6502. My local advanced auto store went to great lenghts trying to find the IFR5L-11. They say when they cross the #6502 stock #, it comes up as spark plug wires and their parts warehouse doesn't have the IFR5L-11 either, and even if they did, you would have to order in quanities of 100. I give up. I'll just pay the $14.82 at the dealer. The #5464 I ordered should be here today and I'm just going to have them send it back since I'm not sure that's the right plug either.