On my '78, I found a horizontal slot, about 30x120mm, on the lower back panel above the exhaust tip. It's behind the bumper, so I never noticed it until the bumper was removed.

Does anyone know what it's for?

thxZ

Maybe heat from exhaust passes through to dry behind bumper and slow rusting.

This has been discussed in a earlier thread. I will see if I can locate it. jlp

I figured it was just a way to keep the muffler cool, but there might be another reason.

Here is a photo of the slot.