Dash reverse light on 70 auto roadrunner

Anyone ever seen a reverse dash light on an auto car? I am disassembling a 1970 roadrunner, 383 auto on column
Never been apart. Numbers match. VIN correct with right rosette rivets.

Are you sure it's a reverse light and not a "Fasten Belts" light?

An automatic should never have received a reverse light.

I once hooked up both to an e-body with 727.
While not 100% correct, sure looked spiffy when lit.

This is how I found it.

Any evidence of it being wired in to anything? Is the lamp harness that goes to bulkhead in place? Doesn't seem right....maybe a factory mistake or replaced in the 52 years it's been around.

The car sat for probably the last 30 years. 20 at the guy I bought it from who never touched it and probably ten or more under a tree mostly covered by branches. It was last tabbed in 1980. While it lived a rough life, most of the car was original and complete right down to the original radio. Not cut up or modified in any way. You can see the slip in socket/bulb in the background of the one shot which is common to this type of light assy. Dash is coming out today.

If you find it was wired in it is most likely a factory error. Odd mistake....but I guess it could have happened.

What style seat belts are in the car? Flip up latch/cover or push button style? Push button style belts would have had seat belt warning dash lamp. Possibly installed the wrong lamp as they are basically the same.

That hanging wiring harness should tell the tale if correct 70 4 spd harness or not.
On a 1970 the light is mounted in the plastic housing as is seen with yours.
Because of this the wiring to the light should have a black wire with white tracer for bulb,
plus a purple wire to ground it as seen in picture provided.
68-9 were in a steel frame and had no need for ground wire, had only one , the light grounded itself.
Let us know what your harness shows.