Sierra 18-2748 MerCruiser 4" Upper Exhaust BootSierra high-quality engine parts are designed to meet OEM specifications. For use on MerCruiser Stern Drive engines.Features: Upper Tube: 4"; Fits MCM 120, 140 & GM V-6 & V-8 engines; Use with: 18-1975-1 Riser with Exhaust TubeInterchangeable with: GLM; 89120; Mallory; 9-72805; MerCruiser Stern Drive; 32-44348T; 32-44348001; 32-44348;