Any tricks to remove them?  I have a 350 lb impact wrench,  I have 1 upper bolt (long one) and 3 lower bolts (short ones) that don't want to loosen.  Short ones are in the rear.  The wrench did take out the others.  Ive been soaking them.  Any ideas would be great.  Block is in the car,  Thanks as always.

Heat the head with a torch, it'l move.

I got all of them out, thank you.