My horns are going out and I am looking to replacing them. I did not see them in the PET. My question is, are both sides the same? Didn't they have different tones a high and a low? Where is the best place to get new ones. I am first interested in stock sound.

Yes, they are high and low tone. I believe they are NLA from Porsche. Hella makes replacements. They come in red frames with black centers. They are a direct bolt in. All the usual places sell them.

The horns are pretty bullet proof. Sometimes they get corroded inside. I've revived them by pulsing power to them in some cases, and by pulling them apart in others. The mechanicals of both horns are the same, but there is a tone adjustment screw on them and some are high tone and some are low. Basic model 914s came with a single horn, upgraded models had dual tone horns. If your horns really are dead, shop around and the usual places (Bruce Stone, EASY, GPR, Our Classifieds, etc) and you should be able to scrounge up some replacements. If you happen to end up with two horns that are the same tone, simply turning the adjustment screw will give you dual tones.

My OE horns were marked on the back as different ratings 335 mHz & 400 mHz - perhaps that was heat stamped into the plastic back housing to indicate what they were tuned at with the screws Mark is talking about, but I'm looking at a pic of them & can't see the adjusting screw but only a probable cover location (not at home now to look at them in person).

The dual tone horns was part of the Appearance Group option package, which was an included option on my 73 2.0.