it's real easy if you take the top housing (thre 13mm bolts easy to get at)off with the thermastat housing attached ,then you can simply take the three 10mm bolts out of thermastat housing pull thermastat out and put in the new one and put it back together as a unit ,make sure you have a new gasket for the top housing.I would use anti seize on all bolts and a good soaking with pentrating oil, WD stands for water displacing and is not really a penitrating oil.........
William Rogers.......