The button on the end of the shifter? Dodge will sell you a whole new shifter arm. I don't know about just the switch.
Sorry, no pictures (the retainer is the ring around the switch):
REMOVAL
(1) Using a plastic trim tool, remove the overdrive
off switch retainer from the shift lever (Fig. 115).
(2) Pull the switch outwards to release it from the
connector in the lever (Fig. 116)
INSTALLATION
NOTE: There is enough slack in the wire to pull out
the connector from the lever.
(1) Pull the connector out of the lever just enough
to grasp it.
CAUTION: Be careful not to bend the pins on the
overdrive off switch. Use care when installing the
switch, as it is not indexed, and can be accidentally
installed incorrectly.
(2) Install the overdrive off switch into the connector
(Fig. 117)
(3) Push the overdrive off switch and wiring into
the shift lever.
(4) Install the overdrive off switch retainer onto
the shift lever.