Brake Tee on Rear Axle and Hardware?

Dr. Diff is your friend:
Brakes :: Rear :: Rear Flex Hose to Hard Line Brass Tee (doctordiff.com)
Mopar Rearend Vent Bolt (doctordiff.com)
The vent bolt holds the brake tee to the housing. A vent is required to prevent gasses/vapors that build up during use from blowing out your seals- generally, anything and everything that contains a liquid will require a vent of some kind.