99 tahoe

Hello all, this site is great everyone has been super helpful thusfar,
I have another question? This is my third transfer case rear seal that the dealer is going to install in under 400 miles any idea what is going on?My truck is still having a clunking squeeky noise comming from the rear when you accelerate from a dead stop and that is why the dealer has it but they sofar are unsure why these transfer seals are leaking after being replaced and only driven 100-200 miles per seal? WOW OH MY!!!! Any idea's