John,

I have never gotten in there and looked at any of this stuff - however I do
know that at one point the vents in the bottom of the doors became
"non-functional" - I'm fairly certain that was done when the vents were
placed in the rear side windows. I thought that was an '86 up change but I
could be wrong.

Maybe both doors originally had that foam peice blocking it off and your
mouse friends removed the other to use as nest material.

Sorry I know that isn't much help but that's what came to mind.

--
Thanks,

Jeff
'85 GL (Gertie)
'90 Carat (Grover - the noble parts donor)
'86 (We call this one Scrap)
'78 Bus (Melissa) Patty's Bus