Viking moved in the early 80's. Not sure exactly when, but it was between the publishing of Different Seasons and Christine, so either 1982 or 1983. The earlier address was 625 Madison Avenue, they moved to 40 West 23rd Street (both in N.Y). This is of crucial importance because most of the books published around that date are fairly hard to identify as firsts.
So how do you identify, say, a first edition of The Dead Zone? We'll look at the book and the DJ separately. First, the book. First Published in 1979 by The Viking Press is useless, they all say it. Absence of a number line? Usefull in differentiating between a 1st printing and a later printing, but useless in differentiating between a BCE and a 1st printing, because neither has number lines. What about size, you say. Some King BCE's are virtually the exact same size as the 1st editions. (The Dead Zone is one of these, It is another, not sure about others but unless you know for SURE that they NEVER made a BCE that size (and how can you really be sure?), then size wont help either (not all the time anyway). What's left? Quarter bound in black cloth with black boards? They're all like that. So now what's left? According to all the FAQ's I've seen, nothing. So there is NO surefire way to identify The Dead Zone as a first edition.
So basically people are identifying the dust jacket, not the book itself. Well, that's fine, right? If you've got a first edition DJ then it must be a first edition book, why the hell would someone put a first edition DJ on a book club? Where'd the first edition book go? DJ's almost always show wear before the book itself, so if you've got a real nice 1st edition DJ it'd be silly to think it contained a BCE book, right? The other way might happen, a First edition book with a shredded or absent DJ might have a BCE DJ, but you'd avoid that anyway assuming the book was also BCE.
Here's the problem. Later printing DJ's are, in at least some cases, identical to first edition DJ's. Christine is one of em, I own a 1st edition and a 3rd edition and the DJ's are completely identical. Date code is the same, price is the same, ISBN is the same, they're completely identical. The Dead Zone is the same way, at least up to the 6th printing (IIRC). So if you can't tell the difference between a 1st printing DJ and a 5th printing DJ, and you can't tell the difference between a BCE book and first edition book, then couldn't your "verified" first edition be a BCE with a later printing DJ? It sure as hell could, and I've seen several copies of the The Dead Zone in just such a manner sell for 75 dollars and up on eBay (as much as a real first edition, in other words. It's not like seeing a BCE Carrie sell for 75 dollars).
So here's where the little tidbit about Viking moving comes in. All the book clubs I've seen that are the correct size were printed AFTER 1983. The Dead Zone was, of course, printed in 1979. Which means the addresses should be different, and they are. The BCE's have the 40 West 23rd Street address, the real Firsts have the 625 Madison Avenue address. The nice thing here is that Viking printed the address on the CP AND the DJ. The later printings were still at 625 Madison, so when you see a BCE with a later printing DJ, not only is the address on the CP wrong, but the address on the CP and the DJ don't match.
Now, this doesn't mean that there couldn't be some BCE's out there that are the correct size printed before 1983. In which case I don't know what to tell ya.