i actually went with the cheaper motorcraft ones but ima go outside right now and pull a plug really fast and see exactally which kind i have and take a pic of one right next to an old one which was in the car when i got it and both are same thread length.. i have said this before im not a mechanic and if it fr dont require money im willing to try anythij ng but will also say this the further you dig into this car the weirder it gets.. like example it wants to hook like way too good.. may be the tires or the aod cuz im use to t5s but it will launch for a mustangThose aren’t the right spark plugs for those heads, they will thread in, but look at the difference in thread lenght. The autolite 25s are likely not sitting deep enough into the chamber, if they even fit properly.
please pay attention here. This is important for you to realize. It appears very likely your car has had the long block from a non-HO 5.0 swapped into it. This is due to the incorrect firing order and the incorrect heads. This combo of parts is found on common passenger car engines like a crown Vic or an ‘88 thunderbird.
if you borescope the cylinders, you’ll prob see the Pistons lack valve reliefs.
iyWell with E6 heads it’s likely down on power. Those heads were pretty weak. Non-Ho 302s were typically in the 180-200HP range. Throw an AOD behind that and it’s down on even more power.
what exactly is wrong with the car? This thread has gone all over the place.
take a photo of the spark plug hole with the plug removed. I can tell from the thread hole depth which plug it will need. But seeing as it is an E6, that info is already known