Just an add-in from my project 1973 to y'all - I'm doing a partial back-sheet replacement (with the extra two rows of rivets) but now have found most of the multilayer panel-to-rib rivets have either sheared or are 75% cut through from the panels working a scissor action on them, from time, heating and cooling cycles, vibration, accident(s)?, tail-dragging, etc. etc..
Even though they are sheared in the center layers they have not moved much, the factory vulkem holds the back flange on and the rivet shaft is still expanded and offset enough at the second of third layer the exterior dome looks tight.
So l be replacing most/all of them with the hardened flavor of 5/32" bucked rivets. If any of you are working there you might look if your shell has a similar situation working... I'll be adding a note to the "Hey y'all, watch this..." refurb thread and hope for better insight on proper repairs there...
The days are short and the night is long and the stars go tumbling by.. . ~Airstream~