this really shoulda been in the ICD section. this is the Technical support section where we talk about bugs and ticks the forum has in it
I'll help you out though.
take a look at the end of the barrel threads. if it's got a little lip stick out the bottom, it's autococker threads. if there's not a lip, it's ICD threads. 2003 was a transition year for ICD from ICD threads to Autococker threads. It's confusing why they chose to do it in the middle, but that's what they did.