H1 has 2 thermostats in the water outlet. Not to hard to replace. When its cool remove the upper hose from the water outlet,you will loose some coolant. remove the bolts, the lower one is the pain in the you know what. To install you set the thermostats in the crossover after you clean out the grouves. They will stay in position and very gently put the water outlet into place and hole with one hand while starting the upper bolts BY HAND and check to make sure the stats are in place.
put in the lower bolts and yes its a chore for the drives side lower one. Re connect hose and top off coolant.
Hope this helps.