A design where the transfer case is not directly bolted to the transmission defines a particular driveline configuration. In this arrangement, a short driveshaft connects the transmission output to the input of the secondary gearbox. This secondary gearbox, the transfer case, is mounted separately, usually to the vehicle frame. An example of this setup can be found in older trucks and some specialized off-road vehicles where flexibility in drivetrain configuration is desired.
This configuration offers several advantages, including increased flexibility in vehicle design. It allows for a greater range of wheelbase options and simplifies the integration of the transfer case with different transmissions. Historically, this design was common in vehicles requiring high ground clearance and robust off-road capabilities. The separate mounting also potentially reduces noise and vibration transmitted from the transmission to the transfer case, and subsequently, to the vehicle’s chassis. The design can also provide greater ease of maintenance and repair, as the secondary gearbox can be removed and serviced independently of the transmission.