When I replaced the dashboard cap, I removed the old one and peeled off the covering from the foam underneath. The foam was pretty deformed, so I clamped it down to stretch it back to its original shape. After a few days, the reshaped foam pad was back to its original fit - so I glued it to the dash with lots of the glue that was supplied with the dashboard cap.

As I recall it looked like clear silicone glue.

When the foam was in place, I glued the dashboard cap in only a few select spots - just enough to keep it in place. The trim pieces along with bottom of the windshield and along the front of the dash helped keep it in place as well. Anyways I figured that I should let it expand and contract freely.

After a couple of years, it looks great and everything is still in place.

waggin
1965 220 wagon
1985 245 turbo wagon