I've never read anything which might suggest such a promotion (if they were decent banjos, it would have been a pretty expensive promo item) but another possibility which comes to mind is that your banjo might have been property of The Texas Company for use in one of the employee bands. I've seen photos and articles pertaining to such bands which they used to have at most of the major branch offices and "Works" (as they used to refer to refineries). If that's what it was, I'd say that it was quite rare.
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Jim Hinds
Columbus, Indiana