UPDATE: II: Thie Buick shown below was featured in the Jan 1950 issue of Popular Science (pg 99)
http://books.google.com/books?id=vSwDAAAAMBAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
UPDATE: Javier provided the following information. I guess there was some competition among the ranches? Below are two photos of other hunting vehicles.
He wrote, This is very similiar to one of the hunting cars used on the King Ranch. The Kenndy Ranch mentioned in the arcticle is adajcent to the King Ranch. Below is a picture of the car made for the King Ranch. (From this link to the University of Texas)
Here’s the hunting wagon from Texas featured on eWillys a couple years ago (seems I’ve deleted the original post related to it:
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David Silberman forwarded this unusual photo from a rare April 1951 issue of Willys Salesbuilder. This one looks like it might have been build on a Jeepster platform.
From this same issue are these two parade float photos: