Truck: '04 Tacoma 4x4/AT/V6, 56K miles on the clock.
Issue: The transfer case oozes fluid, but intermittently. It *appears* the leak is from the rear of the shifter base (similar to what others have posted about here in the last year or two).

Driving around town, the thing stays more or less dry. Heading up I-80 Thursday for a camping trip, I stopped around 3000 ft to make a pit stop and smelled gear oil. Looked underneath and I had oil streaming down both sides of the t-case, and the top of the t-case, behind the shifter base, was wet (puddled). I wasn't beating on the truck, just cruising easy.

I never do water crossings or mudding - 99.99% of my offroading is on dirt roads of various quality (or lack thereof), in the desert or high mountains. The breather-jiggler vent for the dead space between the transmission and the t-case was free and wiggly and the breather hose from the t-case shifter base to the dead space's nipple appeared clear and intact.

Why intermittent and what should I replace first? The shifter base gaskets or the t-case shifter seat or just do it all at once and cross my fingers?

It was so bad I ended up canceling my trip to the desert with a bunch of friends this weekend. Talk about bummed. Didn't want to be 100+ miles from the nearest paved road and kill something in the transfer case.

Oh, also, the t-case is NOT overfilled. Last fluid change I did 7 months ago I let it drain completely and then put in 1 quart (manual calls for 1.1 quarts) of 75w-90 Valvoline. And since then I've done a long drive from the Bay Area up to Bear Trap Basin just a couple of weeks ago, and not so much as a burp. And it was HOT that day. Thursday was early AM and relatively cool

WTF, eh?