Where is the leak coming from? If it is coming out of the block on the bottom of the cylinder you do not have to remove the mast cylinder. The block on the bottom of the cylinder is a flow control valve it has 4 1/4" bolts holding it on to the cylinder. If you raise the front of the truck you can remove the flow control valve and replace it. If one of the lower seals is leaking you will need to remove the cylinder. After removing the flow control valve you will find 2 bolts in the yolk that the cylinder sits in. Remove the bolts. There is a lower cross yolk on the intermediate rail that will need to be unbolted also.