
to FEBO from New Jersey
Looks like a great project.
RT cars will always have the JS designation!
Your car appears to have the RT components; black RT grill, rear quarter louvers, blacked out rear tail panel, and the RT hood.
It is possible that those items could have been added/modified at sometime in the car's history. The hood was available as an option.
JH Challengers in 1971 could have come with a 340 or 383 with the dual exhaust and cut out rear pan. Does the serial number start with JH23H or JH23L or JH23N?
H=340, N=383 -4 and L=383-2. What engine is in the car?
Does the car have the rallye dash?
I would explore deeper and look at numbers on the cowl top, and radiator frame. A JH car with the performance options is still a rare, cool and desirable Challenger.