I'm not going to say this is the last word but I think there are at least two styles of plastic pickup tanks. I'm using an underframe tank from a '73 in my '72 W200. It is a smooth plastic and when it cracked I took it to an RV dealership and they plastic welded it. Apparently RV owners forget to drain the water tank and the dealership has a LOT of experience welding tanks. Now the second style I've seen seems to be a more "rubberier" variety that has a hairy surface. I'm not sure what you would do with that style.