Smith and Wesson 649

I'm a long time member here, and not a member of any Smith forums. I was wondering if any of my Ruger buddies, who also own Smith's, might be able to answer a question for me. I have a stainless 649. Shrouded hammer J frame. Would anyone be able to tell me the year serial number BBN prefix was built. I know all about calling Smith and buying books and all but I just thought maybe someone might have the info handy. If I'm crossing any lines asking a Smith question here then please disregard. Thanks!

BBN was 1988. Sometimes a dash # helps.

Thanks very much sir!