2005 gmc 1500 z-71

[barry1982]

Hi Guys, I just picked up an 05 GMC. Having starter trouble, one of the bolts that holds starter to engine block was extremely hard to remove. Discovered the threads on bolt are "galled". Want to clean up the bolt, and run a tap into block before installing new starter. Needed a 13mm socket to remove bolt, so thinking bolt is metric. Does anyone know the correct metric size and thread pitch? Need this info so I can get the correct tap/die. Thanks.