Spark Plug discrepancy
 

Well, due to some recent running trouble, doing some maintanance on my Blazer, and it appears plugs are due (and have almost no electrode left...)

However, I found an issue... When I last replaced them (July '09) 30,000 miles ago... Delco Rapidfire 12's were called for. However when I was looking up to price check today on AutoZone's website, it's now calling for Rapidfire 14's?

Which is the correct plug? Is the 14 just an updated version of the 12 or something? Rapidfire 12 is what I have in it now...
Just want to make sure of the correct plug to buy to change them out this weekend, and different plugs being called out now just seems... odd.

honestly,id just stick some copper ac delcos or ngk's in it and be done with it. unless you like spending more money.

I agree. AC Delco 41-993 with a gap of .060" are what it came with originally. Should last 100K miles.

check the emission sticker under the hood
It tells you the stock ac delco plug # and gap

30k out of spark plugs isnt a whole lot....

No nobody knows why it used to be 12s and now 14s?

Rapidfire plugs are platinum, old technology. AC Delco 41-993 plugs have iridium electrodes, and they replace the old double platinum plugs.

So a Rapidfire 12 is a platinum and a Rapidfire 14 is an iridium?

All Rapidfire plugs have platinum electrodes.
RAPIDFIRE Performance Platinum Spark Plugs | Auto Parts | ACDelco
Spark Plugs - Iridium Spark Plug | Auto Parts | ACDelco