Not clear what you are asking about.

The torque converter fluid can not be changed by itself, it is a common circuit with the transmission. You drain and refill the transmission, 4 or 5 quarts, and that gets about half of it (as the torque converter doesn't drain when the transmission drains).

But the transmission isn't near the front differential.

__________________
2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue