My rear brake tee is leaking, how to fix

I was surprised to see something leaking at all. The car has been on jackstands for six months...hot and cold weather but heated garage, min.42 degrees...91 in there yesterday. Can't be overfilled since the "pig" filler hole is on the side, correct?
If the brake line T is leaking it will be easy to test, set in the car and apply pressure on the brakes and hold it down hard for about a count of 10 and look and see if brake fluid seeped out, if it did put a line wrench on each fitting and tighten, these are steel flair fittings and need to be good and tight
Remove the over flow/filler plug and see if the rear 80/90 WT oil comes out..
You should be able to tell if it is brake fluid on the floor because it is very thin and will soak into your concrete and not puddle like rear gear lube will.

A line wrench is a must on the brake lines to get them tight