[78RedExpress]

98 Dodge Ram 2500 V-10 Quad-cab non dually 4x4 with original owner 120,000 miles

Was unscrewing the rear axle fill level checking plug after a 5 minute drive and noticed a "POOF" when the last teflon tape coated thread unscrewed. Made me think there must be a small amount of pressure in there. Oil level was just at the hole and ran out.

If the good sized hose in my pics is the venting tube then why does it appear to run through the brass T shaped fitting in the top of my left axle tube that also has brake lines running through it ?

Getting ready for some extended towing and obviously don't want to have an axle problem that had been staring me in the face beforehand. Tried applying small amount of air pressure and then full suction to the tube with the plastic end out of it but wasn't convinced air moved either direction although it does taste and smell of gear oil. My plastic end ISN'T a check valve.

Is this a problem I'm describing? 30K miles ago i had replaced the left rear axle seal when it had leaked into that brake housing.