We can assist in sourcing a replacement fresh water tank for your 2005 Tiara 3600 Open boat. To ensure proper fit and compatibility with the Ameri-Kart original design, please provide the exact dimensions of the installation space (length, width, and height). Once we verify that the tank matches your space and requirements, we can confirm if modifications or custom fittings are needed and provide an accurate quote. We are committed to helping you find the closest match or an exact replacement to meet your specifications.