I replaced the seal on my bedroom slide-out. It took about 4 hours to do. The hardest part was removing the old seal and it's residue. You will need to measure the total length of the seal and order that number of feet plus about a foot, because the seal is sold by the foot and you will have to cut it to fit your slide. The new seal will come with the adhesive already on it, so application is easy if you are careful.
Beaver Coach Sales in Bend, Alliance Coach in Florida, or Monaco should have the seal material.
Gerald