At around 87k miles, I had one of the heater hoses that runs around to the back side of the motor burst. The hose split right where it connects to the back of the engine. When it happened, I immediately thought "shit, it's the valley pan". Luckily, after sticking my hand back there I felt the tear in the hose. Much easier repair then the valley pan gasket.
There are two hoses, #11 and #12 in this
Real OEM diagram. They run along the driver's side of engine from the heater valve area to the rear engine cooling manifold. Check those hoses, and you might get lucky and have that be the source of your leak.