1 bolt will be hard to get out, use an open end wrench and break it free and then spin it loose w/ your fingers till it hits the back of the pully - you dont need to take the pully off first- but you will have to after. the pump is easyest to take off from underneath. then you will need a puller to get the pully off ~$12-15 and all you need is to open the new box and it should have a bolt and washer in it to put the pully back on.