Go ask this question in the FE forum. The upper row of bolts it famous for becoming one with the head flange. There are several ideas on how to deal with it. Soak it with penetrating oil every day for a week or two after running the truck (while the parts are warm). Do a search on the candle trick on this board.

The upper row of bolts are so bad about seizing that some people just drill them out and replace them with a bolt and nut.