1988 Wolfsburg Edition with the AC Ducts down the center.

My top ac ducts were cracking and falling down due to broken plastic under the metal plate and along the top sides.  The ducts are being held in place from the top and over time that starts to break down.  To fix it, I put a thin aluminum band (1 inch wide by 1/8" thick)around the outside of the duct and then put the ducts back in, trapping the top of the band between the duct and the roof.

Roof of Vanagon
Aluminum strip
plastic duct
metal plate

The aluminum strip was easy to bend into shape and I did not have to drill any holes in the strip either.

It looks good and the best part is that the ducts should not fall off...

If you want pictures email me...

Robert