See that the 4.0 V6 calls for Platinium Motorcraft SP498 (AGSF24FM) spark plugs. Motorcraft plugs are made by Autolite. Autolite platinium plug AP5143 appears to be identical but is about $1 cheaper per plug. Does anyone know if these 2 plugs are identical? Looked around for compatibility and substitution guides but haven't found the specs on these plugs.