Chateau Boswell - 1983 case of 6

[Reg]

My wife bought a 6 bottle case packed in a wood box of Chateau Boswell of Napa Valley - 1983, Cabernet Sauvignon at our local Rotary Club Charity auction a couple years ago. The donor swore it was some valuable wine. My wife swears it was an "investment" - I think it was just a "donation". Can anyone tell me what it is worth or where I could go to find out? And where I could sell it if I should so choose. Thanks!