So, I'm new here, have a 2006 LS 3.9L. 150,000 mi. after removing and replacing intake manifold for an engine miss and gasket leak, I started chasing a cooling problem after reassembly. I had replaced some of the cooling components since I was there; water pump, radiator, thermostat and housing, etc. Finally found problem, after market thermostat and housing. the cooling fans kept coming on, top hose hot, lower hose cool, not overheating, BUT OEM cured it. the after market housing and thermostats are not the same! even if they are rated same temp. the engineering and design don't work like OEM. and OEM on line not that expensive.