This is a Model 45 which should be depicted on the ID Plate that's attached to the rear engine mounting rail on the drive train side.

If the handlebars are original then it's quite possibly a Craftsman version of the Model 45 which was a store branded release. This one has had an engine change to a current model Briggs unit.

Cheers,
BB.

I live a 24 Hour lifestyle, but every now and again I seem to fall asleep, well at least that's what my wife tells me.