Most RV black water tanks from the late 1990s and early 2000s, including those made by WEVAC Plastic Corp, are constructed from polyethylene rather than ABS plastic. Polyethylene is flexible and has a waxy surface, making it difficult for standard adhesives or epoxies to bond effectively. For repairing leaks, we recommend using specialized polyethylene repair kits or plastic welding methods designed specifically for this material. If you can confirm your tank's material or provide a photo of the crack, we can guide you to the best repair. Regarding replacement tanks, we offer black water tanks in various sizes. If you can provide the depth measurement in addition to your width and length (19-3/4 inches wide and 53 inches long), we can help you find a close match for your 5th-wheel trailer. Feel free to reach out for product recommendations or assistance with repairs or replacements.