The "lock" is what I thought it was.... It has been a looooong time since I've seen one like that, and can't remember for sure if it was a Series LR, or an old VW transporter ( or both

).
But if memory serves me right, the rubber button portion is (was) a one piece dome shape with a pin to hold it on the shaft ( like a mushroom).
If it was in front of me, I'm sure I have a window guide, or door stop that would work ( as much as people here think of me for glass, my core business is mainly in residential and commercial door hardware).... you can email me pics of the mechanism with the rubber removed and dimension, I can see what I have that may work. I could tell you what you need to source, or possibly send you some.
Those grilles are definately add-on. They look like HVAC registers.
If you have pics of the inside at that area, I could make a good educated guess what it was for .
Dave
dsd277@sbcglobal.net
.
The Trojan Horse... the 1st Pinz used to covertly carry troops into battle .
ATL Pinzgauer XM 718K TUM(HD) 6x6 FFR (aka The Green Grail)