GM Service Manual Online
For 1990-2009 cars only

Object Number: 640601  Size: SH

An identification tag is attached to the rear half of the transfer case. The tag provides the following information:

  1. Model number (1)
  2. 1.1. First Digit--1 =Single Speed, 2=Two Speed
    1.2. Second Digit--3 =T-Truck, L-Van, 4 or 6 = GMT 800
    1.3. Third Digit--1 = Manual, 3 = Electric Shift, 6 = Automatic, 9 = All Wheel Drive
  3. Assembly number (2)
  4. Serial number (Date & Shift Code) (3)
  5. Low range reduction ratio (4)

The information on this tag is necessary for servicing the transfer case. If the tag is removed or becomes dislodged during service operations, keep the identification tag with the unit.