Proflow Water Neck, For Holden Commodore LS1/LS2/LS3, 90 Degree, Swivel, Billet Aluminium, Black Anodised - PFETH-808BKPart Number: PFETH 808BK Proflow's new LS billet thermostat housings not only look good, they also come with a new high temperature Viton o ring design, which means you don't need to use old rubber seal. They suit a standard 56mm diameter thermostat which is the same as the original LS2 LS3 versions.