trans and tcase seal question

hey first post here. ill try to keep it short. about 8yrs ago i bought '04 trd 4x4 xcab man trans. was in great shape with 52k. hardly drove the truck, about 3k a year. still has just 77k today. anyways a couple years after owning it i was underneath doing maintenance. changing engine oil or something and i noticed gear oil seeping through the tcase-trans junction. was alittle stumped that the seals would need replaced so soon but whatever.

pulled tcase off to have a look. not being able to determine which seal was leaking i just replaced both, output trans and input tcase with factory seals. didnt appear to be any major grooving of the tcase input shaft. got it back together and to my suprise it started leaking shortly there after. didnt have time to mess with it so i let it go for a few years

fast forward to last month. got time to pull tcase again. still couldnt determine where leak is. assumed one of the seals, then dripping straight down. replaced rear trans seal with skf, left tcase input seal alone. no pronounced shaft grooving. did happen to notice the tcase input shaft has a bit of up-down-side to side play. got it back together and drove for few days. dam thing leaking again. i have been putting the replacement seals back to the same flush depth and the originals which may have been a mistake

question . is a bit of play (.010" or so) in input tcase shaft normal ? if so then perhaps i just need to take some new seals in .030" or so deeper and get to fresh shaft surface. if play isnt normal then i guess that may be causing the leak but how could the bearing be toast at just 77k easy miles

 

It could be something as simple as a blocked vent... at the top of the Tcase there should be a vent hose, see if it is blocked. I have heard of blocked vent hoses pushing lube past the seal(s). There is a similar araingment for the front diff, rear diff and trans itself. All "should" have hoses on them routed to a higher point to prevent water ingress when crossing streams.