Aha! Gotchya you elusive little sucker!

I have taken one small step forward: the Briggs and Stratton engine number is

Model Type Code
281707 0415-01 90042331

This is great, but doesn't get me closer to identifying the mower model number. Or does it?

Are the model numbers stamped into the chassis or were they on stickers? Again I looked all over and found nothing.