Wood at base of vista views?

[malconium]

I am removing the inner skin of my 1973 31' Sovereign. This of course exposes the vista view window shade tracks. I discovered that there is a strip of wood along the bottom of each one that seems to be acting as a spacer of sorts. It looks like maybe 3/16" or 1/4" plywood. It does not strike me as being original for some reason.

Has anyone seen this same type of thing?

Thanks,

Malcolm