E-Bodies.org Cuda Challenger Forum

Here's another pic that may help.
The 70 Challenger light bars are curved to match the different shape of the 70 Challenger dash pad foam.

The 3 screws that fasten to the metal dash core are identically located on all E body light bars.  The curved part of the 70 light bar is recessed to allow these screws to be in the same place as other E body light bars.  This allows the metal dash cores to be identical for all E bodies.  The dash cores can be drilled for options like air conditioning or stereo speakers, but they'll fit in any E body, only the foam is different.  If you need a 70 dash core for restoration and you can only find other E body cores, you're still ok to send it in to the company of your choice for new foam & vinyl.

Tav

This pic illustrates the difference between a Rallye light bar and a Non-Rallye light bar.

Different number of lenses and different color of lenses.

The extra bulb seen attached to the left hand end of the Rallye light bar in this picture is the Title Lamp that's only available as part of the A01 Light Package option.  It could be installed on cars with or without a rallye dash.

Tav

Here's the back side for reference.

As far as I know, the 72-74 part numbers are the same as the 71 part numbers.
The rumor that they were different came from a misunderstanding that Jules D'addio had. Jules thought that Rallye light bars were for 70-71 cars, and non-rallye light bars were for 72-74 cars. He was confused because he was only sent light bars to restore, and didn't get to see the cars much. He posted that info on another Mopar forum.  We got him straightened out about the light bars, but MCC copied the bad info from that forum and put it into their book, distributing it to many other people. 
The MMC book is always a work in progress, so I hope this error has been corrected in it by now.

You're welcome! 

I've been busy working on my 70 Road Runner.  Getting close, might start it up in the next week or so.
I couldn't resist this topic though.  While I'm here, I guess I'll look around a bit and see what I've missed.   :)