Spark Plug question

[shorty]

Its possible i have asked this question here before.I just do not remember having an answer
so awhile back i changed my plugs on my 95 5.0 and out came a set of autolite AP104
the part store shows the plugs going to a 4.6?
I know the ones i put in had shorter threads.
So what i want to know is: Is there any reason one might put these in? other then just not knowing what there doing.
The car ran fine with them. But from what i have read they shouldn't have fit in the 1st place
Im about to do a tune up, and Im curios if i should put these back in the car?

 

[ScottyDsntKnow]

If you are about to do a tune up you're getting new plugs anyway. Or at least you should be. Autolite 25s are correct for E7 heads and you might as well do the plugs now while they are out of the car.

 

[mikey94gt]

What he said.... autolite 25's are hard to go wrong with.

 

[Magic]

What heads are on the engine?
Stock E7 or GT40 irons?

 

[shorty]

What heads are on the engine?
Stock E7 or GT40 irons?

This ^
I'm assuming E7 heads. I'm just stumped on why someone would put these plugs in the car.
When i do a cross reference on these plugs, they show to fit in a 94-95 cobra or a 4.6 motor.
This is what has me confused.

I will also add, i changed these plugs some time ago, and put the motorcraft plugs in for the E7 heads. Of course I'm not sure if its just my mind thinking to much, or if the car actually does drive crappier.

 

[Magic]

Have a look for any identifying marks if they are a GT40 head.

||| bars on the ends and "GT" next to #1/#8 spark plug = GT-40
|||| bars on the ends and "GTP" next to #1/#8 spark plug = GT-40P

Or read the link here:

http://www.fiveohinfo.com/performance/gt40-gt40p.html