What are the best spark plugs out there for a 5.0 thats stock besides the GT-40 parts?

Personally I use Autolite's in everthing I run. They work fine and are cheap at Wally World...

I would go with BOSCH Platinum Series. I have them in my 88. I like them.

Personally I stay away from Platinum plugs in the 5.0s. If your car runs better on platinums then you have another problem or weak spark...platinums make it easier for the spark to jump.

I recommend Motorcraft or Autolites....I usually run an ASF 32C in the 87-95 engines which is one heat range colder than stock...allows a little more aggressive timing ;).

Don't buy into the high mileage promise of some plugs...they are a wear item and should be serviced like anything else. I had an LX that I bought with 123K on the original Motorcraft plugs...even though the electrode was very worn the car still ran great.

If you run an MSD or other aftermarket ignition box then plan a more frequent plug change...they do wear the plugs out faster.

I have never had a problem with them but I wouldnt know if it runs better because when I put them in I was swpping out the motor. Looks like you just helped both of us out. Thanks.