Sorry not mustang question but here is the situation. I have a 2000 expedition with 4.6. . I am now close to the recommended replacement at 100,000 miles. Here is my problem. The plugs that are in it are factory original motorcraft AWSF32P. I went to buy new plugs today and was told that new number is AGSF32FM. Now here is the problem. The plugs that I am told that are correct for the truck are different. The threaded part is twice as long. Being it is going to go further down in the head. I have checked with pepboys, autozone and advance auto and all say the same thing. They all call for that different number. Will it make a difference? Can I use the plugs that have twice the thread amount without damaging the engine?