Not sure if I'm reading your description right, but the frame joint is originally sealed with clear silicone caulk.
 
Alistair

> On Mar 18, 2017, at 11:43 AM, Toomey Douglas <drt@UOREGON.EDU> wrote:
> 
> The 2 side, slider windows on my 87 vanagon were recently removed for body work.  Reinstalled with new seals.  Both windows leak, so retried the install.  In the process we found out that the leak appears to be occurring on the anodized aluminum frame there the two ends meet.
> 
> Has anyone else encountered this issue and are there suggested fixes?