According to the information I have, this is a 1936 Buick that was rebodied by the Spanish firm Salvador Caba (Cabanas) and it was used as transport for his family.
I do not have the years of construction for all of his conversions, I suspect it was after the Spanish Civil War and could perhaps been after 1945, but he did a large number of such rebody jobs mostly on American vehicle chassis.
Here is a better photo.
Bill