04 4x4 trans seal question

ill try to make this short as i can. bought 04 trd 4x4 xtracab v6 5spd about 10yrs ago ( 2010) with 50k on the clock. was in like new condition. still only has 85k now. couple yrs after i got it, i was underneath doing routine maintenance and noticed small amout of oil residue at the junction of the trans and tcase. 50k seemed very early for a seal to be leaking but i figured maybe it was buggered at the factory or something. pulled tcase off and replaced rear trans seal and front tcase seal with oe seals. seems like the oil was from the trans rear but its been many yrs and cant recall. shortly after replacing these seals it was leaking again. i dont drive the truck much so i didnt pull the tcase off again for few yrs. when i did pull it off again i replaced both seals with oe , since i couldnt tell for sure where the leak was but im more confident its the trans rear.. soon after the oil was leaking again. so again i pulled the tcase off and replaced both seals but used skf brand this time. again its leaking soon after.

first seal change i thought maybe i bunged the seal but the next two seal changes i made sure to becareful. the tcase shaft is in perfect cond with no burs or grooves. ive tried installing the seals flush, beyond flush and at the depth in the service manual, nothing makes a difference. there is a small amout of radial play in the front tcase bearing bit i cant see it being a problem and maybe its normal.

recently ive noticed there appears to be two top hat vents on the top of the trans near the gear shifter. one is completely dry but the other has some oil coming out. is it possible that on the highway speeds , its building so much pressure its blowing past the seal ? im completely stumped at the point. ive pulled the oily metal vent cap off the see if that makes any difference. ill also replace seals one again to try and figure this out. local guy said maybe theres a hair crack from the casting process but i dont know. im not even 100% sure that its the trans seal but thats where logic is leading me. lets say im 99% that its the trans seal.

 

Not sure but I have read it’s a delicate process to get the t-case back together without damaging either seal.

As far as the vents go, they look similar to the rear axle diff vent.

My axle vent got plugged up and was not letting the gas pressure come out and blew it my axle seal.
10.00 vent causes a 500.00 Or so repair for me.

I would probably replace both those pressure vents anyways. They are inexpensive