This picture shows how far a torque tube propeller shaft extends past the torque tube housing.

This picture shows torque tube rear yoke bushing wear marks on the rear yoke.
When the rear yoke is slid onto the torque tube propeller shaft splines,
the wear mark farthest to the right is flush with the end of the torque tube housing .

The rear yoke normally rides about 2 1/2" onto/down the propeller shaft splines.
That is more spline overlap that is on the front yoke (upper left) bolted to the transmission main output shaft.

When the rear axle is not moving up or down, this Picture shows the position of the rear yoke on the propeller shaft splines.
This is the position of the rear yoke most of the time.
Depending on how much the axle moves up and down, will determine how much the yoke slides/rides on the propeller shaft splines.
This picture shows bushing wear marks when it gets hot.