i am looking to change out my thermostat in 87 420 sel, not shure which one is it, i believe it is the lower one by the alternator, if so is there a trick to getting the housing off, looks pretty tight, when installing a new one how should it be installed, i noticed another thread it said with arrow point up, the one i got is a 80C behr and don't see an arrow, any help appreciated. thanks, pics of location and or chance procedures greatly appreciated. thanks