If the water pump look at the bottom hole from underneath while its running. If the intake check the front between the block and intake right above the water pump and also it may leak into the "V" between the valve cover and intake so use a light and look there too. If its the V and you park on a grade it runs down front or rear (front down hill then runs down the front). Also, there is the famous leaking heater core but you will smell that one in the cab. Any hose could also spring a leak but so far never had one leak in my 4 blazers 98 up.