Is there such a thing?

I would imagine it would be made up of separate small block off plates.

Anyone have any pics?

The A-body heater delete would be the same one used 67-72 cars. Used mostly in South American and Hawaii A-bodies. And also borrowed for 68 Super Stock cars.

Many of the South American A-bodies used the Rallye dash cluster. They use very simple flat block of plates that clip into the heater control slots and radio holes. Since those holes changed from 67-71 US cars, I would think the location of clips you cant see change which would change the part numbers.

I've seen a Mexican 69 Barracuda that had part of the heater plates left after hacking (car was a mess). Pics below. Notice where they put the radio. You can't put it there in a car with a heater.

I've never seen part numbers for the radio nor heater block off plates.

Here's an old thread on the subject: https://board.moparts.org/ubbthreads/ubbthreads.php/ubb/showflat/Number/4640496/site_id/1

.. and 73-4 ( although they were not rallye ) didn't use a plate but had the heater area molded closed like this one I have.

Did the radio delete (not optioned) versions of that have a molded in blank or separate piece?

67-69 Dart GT/GTS/270 had molded in blanks for heater and/or radio.