66 Plymouth Barracuda trunk panel below trunk

Probably a different part # because in 66 they changed the Key Lock Cylinders in the doors/ trunk access... ?? So the Hole in the panel is slightly different ?
Best to find a 66 Valiant / `cuda... but if you can't, don't overlook the 65 model year for that panel...

The door lock cylinder is definitely different 65 to 66. But you can use a 66 door lock gasket on the trunk lock of a 65 Barracuda. Same trunk lock both years? I no longer have my 66 Barracuda so can't say.