Verified answer

The gasket sounds like it's blown.

It could be coming from a few different places, depending on where it is located. The two halves of the transfer case hare sealed with ruber silicone and often leak there, as do input and output seals.

Clean it off well and keep an eye on it. Parts houses sell a dye to put in with the oil to locate a leak, but you would need an infra-red light to see it.

Make sure too that what you are seeing isn't blowing back from the engine or trans.

check the fill/ drain plug screws for taughness. tighten if they can loosen by hand. The gaskets may need replaced, or just may have a small leak. This is an easy and cheap fix

simple fix, crawl underneath the truck with the right size box end wrench, and tighten up the bolts on the transfer case housing.the nv-231's bolts will loosen up a lil bit around every 50 to 60k miles. just re-tighten,replenish any lost fluid and drive on

why not have the transfer case gone through? they can be fixed and re sealed, maybe cheaper than replacing.