The WSS was a dress-up option on Challengers sold in the western part of the U.S.

It included the following:

"Western Sport Special" Decal
Vinyl Roof
Wood Grained Instrument Panel Appliqué
Remote Control Mirror
Rim Blow Steering Wheel
Sill-Belt & Cowl Moldings
Front Splash Pan Scoop
F78X14 White Side Wall Tires
Rear Astrotone Painted Appliqué (Argent Painted Tail Panel)
Pedal Dress Up
Bumper Guards Front and Rear Rubber Inserts
Rallye Wheels.

I guess that you could order any engine with the WSS option. However, there was never a 383 T/A. If you found one it was not the original engine.