Hi,
I found some interesting information on another forum that explains how the Murray model numbers work.
It won't tell you your model number but will show you what it should look like.
Apparently they have changed the way their model numbers look three times.
Anyway, here is the page address: http://www.mytractorforum.com/showthread.php?t=145127

They also have a complete section on Murray mowers.
you may find some information that helps you there.

Regards
Murray

Cheers, Murray