I have leaking transmission, I need some tips from an expert on:

1- to replace the tub seal, do i start from the top of the shaft by 1st
removing drive block Asm, then removing the Stud, then center post, and
so on?

2- since oil is floating, does that mean there are some water inside
the transmission that need to remove?

Is it OK to replace the old oil by holding the transmission upside-down
overnight and unplug the oil fill plug? if so, how much new oil (90wt)
should i add?

3- I removed the stud and screw but the DRIVE BLOCK is not moving, how
do i remove it?

Thank you for your help

Wasban