Argosy? 1979 by Altantic Research Corp
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This is speculation on my part, but it may be that it is an Argosy/Airstream motorhome that was built by the specialty division that Airstream maintained until relatively recently to build custom coaches for businesses. The VIN bears some similarity to those attached to Argosy travel trailers of the time --- the first portion of the VIN is different (prior to the S); but the balance is similar. My suspicion is that the S may designate Specialty or Special Order.
If the balance follows the mode of the travel trailers, the 9 would designate the last digit of the year 1979, the V would designate Versailles, OH as the factory location, and the last four digits would designate the sequential production number.
Good luck with your coach and solving the mystery!
P.S.: It appears from brief research on the internet that the company mentioned on the tag was/is involved in the Aero-Space industry -- and may have had use for such a vehicle for on-site testing.
Kevin D. Allen
WBCCI (Lifetime Member)/VAC/Free Wheelers #6359
1964 Overlander International/1999 GMC K2500 Suburban (7400 VORTEC/4.11 Differentials)
1978 Argosy Minuet 6.0 Metre/1975 Cadillac Eldorado Convertible (8.2 Liter V8/2.70 Final Drive)