After a short drive, I smelled coolant and there was a trail behind the truck.

It seems to be leaking from near the bottom of the engine above the transmission. On the passenger side, looking in the wheel well you can see what looks like a sensor of some type. Coolant is leaking around that. What is it? 1996 F150, 302, 4x4.

 

If it's below the exhaust manifold, it's the block heater which is in a freeze plug bore. If it never gets below ~10°F where you are (where are you?), you can delete it & just put in a regular freeze plug.

If it's running DOWN onto a freeze plug, it's the head gasket (BAD).

If it's above the manifold, it's probably coming from the intake gasket & running down the valley out the back onto the trans.

 

Here's a picture. It's leaking around the plug that's circled.

 

That's the factory block heater.

 

Thanks Steve.

Have you ever replaced this freeze plug? I'm think I'm going to attempt to do this myself. Any tips?

 

It's not a freeze plug - it takes the place of a freeze plug, so if its mounting plate is leaking, you could delete it & put a freeze plug in. But if it's just the O-ring that's leaking, you can replace that.