Montero 3.0 DOHC leaking coolant

I noticed on my girlfriends car that it is leaking coolant on the passenger side, it appears to be only down the passenger side. It's leaking at least as high as the exhaust manifold bolts, but not on top of the valve covers because that is dry. I'm guessing that it's the head gasket but it's just the water jacket leaking because the coolant and the oil are still clean. On of the former mechanics at my work suggested putting stop leak in it but I wasnt sure of doing that due to the fact that both the intake manifold and fuel injection have coolant going through them and the coolant intakes on the manifold are only the size of a vaccuum line I didn't know if it would plug them up anywhere....anyone ever done this or maybe might know for sure what is leaking?

just so you guys know if you see this, it turned out to be a hole in the water pump from wear that leaked through the back of it and down the center valley of the engine to where it came out near the manifold making it look like it was leaking from that area...It ended up just being a wear hole in the water pump after all even though from the front there was no coolant coming out like you would expect with a water pump. Found it via a pressure test of the coolant system.