Can some one shed light on why the bolt hole pattern on left side of housing is different than on a stock cast iron housing? Everything appears the same except the aluminum hosing from 440 Source has a hole at the base of the thermostat housing, inline with one of the water pump bolt holes. The 440 Source website says not for use on cars with factory air conditioning. Can anyone explain why it wont work on a engine with A/C and what the extra hole at base of thermostat housing is for?
