Holden 6 cylinder thermostat housing spacer kit, includes 3 hex head bolts, flat and spring washers as well as two thermo gaskets and 10mm aluminum spacer. The replacement thermostat housing and base are NOT included and can be purchased separately and are examples of other products also manufactured by Aussiespeed. The base will bolt to Holden 9 port and 12 port cast iron & aluminium heads.The thermostat housing base spacer is 10mm thick  Aussiespeed manufacture a range of alloy rocker covers, manifolds, tunnel rams, air cleaners and hood scoops.