No, Dodge trucks (and most modern 4x4 vehicles) do not use a purely vacuum-based system for their 4-wheel drive engagement. While vacuum may be used for some *auxiliary* functions related to 4WD (like shifting transfer case actuators on older models), the primary engagement of the transfer case and front differential is typically done using electronically controlled actuators or hydraulic systems.
Older Dodge trucks might have had more vacuum-based components, but modern ones rely heavily on electrical and/or hydraulic systems for more precise and reliable 4WD operation.
