Click here:
http://www.wholesalemarine.com/pc/S-...+520290-1.html
Remove the old ones. A socket, hammer and chisel are your friends. You will need at least 5 beers and 3 cigars (if you smoke) to complete this job. After the old ones are removed you need to clean the hole out real good with a round file or what ever will work. Some of the hardwares stores carry a circular wire brush that mounts to a standard drill and that will help to remove any old calking thats in the hole. After you get the big stuff out clean the hole with acetone. Next cut the tubes the right length using a pipe cutter. Swab the hole and the tube with lots of 5200 and use flaring tool to seat the new brass tube in place. Buy a couple extra brass tubes just in case you screw up one. Good luck!
One more thing...I will caution you that the brass tube is mounted in a wooden block between the deck and bottom of the hull. This wooden block must be sound (not rotton) to support the brass tubes. If it is rotton it will need to be replaced. Another option is to route the scuppers out the back of the boat which is what a lot of us tend to do anyways.
strick