A combination landing unit and seal assembly is shown for engaging and sealing within the internal bore of the liner within a well. A special latch mechanism carried on the seal assembly includes an externally threaded latch collet which can be stabbed into the setting sleeve threads which are normally provided in the interior of the liner for use with the running tool which installs the liner in the well bore. An integral seal assembly is carried in the assembly in an upward extension of the landing unit and floats within a tubular extension of the landing unit. A plug can be installed in the landing unit to allow the seal assembly to be retrieved to the well surface without killing the well.