Most books like the Red Book, etc, have errors in them. We try to base everything on GM documentation and real cars. Lot fewer mistakes that way.
Craig,
That's a familiar story. I've heard of several L78 cars with the 3 speed trans swapped cause noone believed it was original.
If you send me the VIN off that trans and the trans code, I'll see if I know anything about that car or if we run across it in the future.
One thing I don't know for sure. If you ordered a SS and got the base trans, was the trans included in the SS price or was M13 / MC1 a mandatory option ($79) that you had to pay for? I think it was the latter, but I'm not positive. Never seen a window sticker to confirm it.....