Abstract: A split-installation drainage arrangement for a convertible vehicle topwell assembly adapted for storage of the top in a downwardly folded position. The plastic shell-like topwell includes a floor molded with right and left side water collecting areas each terminating in a drainage recess. A sub-assembly, adapted for transporting water from an associated recess to the exterior of the vehicle, includes a one-piece discharge fitting and a sealing grommet interconnected by a flexible drain tube. The tube has one end attached to an exit spout of the fitting and its other end adapted for insertion in a body panel aperture by means of a snap-in sealing grommet. The sub-assemblies are readily installed in the vehicle body prior to the installation of the topwell. Each fitting has a collar adapted for snap-in mounting in a body support panel oval-shaped aperture.