plastic welder for gas tanks

does anyone have/use one for this operation? was thinking about removing a section of a plastic tank that has a screw on top and adding it to an tank that has a fuel pump module held in with a screw type clamp. 88-90 dodge trucks have module held in with screw clamp, 91 up have screw on top holding module in. what is best/most reasonable one out there to do what i want to do?