What were the exact guitar and amp used by Kurt Cobain to record the opening chords of Smells Like TeenSpirit?

The sound he got was similar to a Strat on the Bridge Pick-up, but he was known for using Modified guitars. Therefore any specific details of the whole set up used to get this "dirty" Strat sound would be greatly appreciated. I am referring to the clean sound on the album and not a live performance of the song. Many thanks for any details!