Moderator Post: >I am guessingbyHandyman on 06/23/2009
BJ is correct in his reading of the model number. I have the same model, and it is on the black and gray nameplate, which is on the back of the mower, behind the seat, above where the trailer hitch would go. Stoop down and you'll see it without having to lift the seat.
I've searched for the model number on the current Murray site, too. My guess is that this mower is so old (I bought mine from Lowes in July 1987 and am still using it) that Murray obsoleted it, thinking the mower probably wouldn't last this long -- 22 years later.