Bad Heater Core???
 

I have a 99 Silverado 1500 5.3 I recently noticed a lot of fluid under the truck itself, but cannot tell where it is coming from. I checked the passenger side of interior for wetness, but found none. Then checked the driver side and found the carpet and underside of floor mat to be wet. Not noticing any antifreeze smell. I thought at first it was transmission fluid, but that fluid level looks ok. Coolant level also seems to be dropping, but not quickly. Please help...

Ok. Checked antifreeze levels again... everything appears to be fine... pretty sure its coming from the transfer case... possibly coming up through the floor on the driver side to wet the carpet. Anyone have an experience similar to this????????? Under the truck it is wet from the transfer case to the rear of the truck

What is it wet with?

What NullHead said.
What kind of fluid ?