According to AZN who posted this previously, VTG = Verteilungsgetriebe = transfer case. There is a VTG control module for the transfer case.

The classification resistor is part of the transfer case. Here is how it functions:

BMW TIS - E83, E53 xDrive electric servomotor with incremental sensor and classification resistor Construction Key Explanation

__________________
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