Honestly, never looked for it on my engine. The mechanic that did my pre-buy/annual confirmed what the seller had told me, it's a narrow deck. The mechanic that works on it now reconfirmed. Both mechanics are old time cub guys, one has his own engine stc.
I was was interested in this thread because I thought if I ever had an excuse to do something with my engine, I would like to have 160hp. Alas, as of yet, no excuse. Cylinders are tight and no oil usage. Only problem I am having, oil temp too low. With 99 deg oat and dragging around amphib floats, I think I saw 190 deg oil temp once, otherwise usually 160- 180. At 35 deg oat with the winter front, no floats, I can get it to 185 deg I've yet to fly it with any colder oat, almost afraid to.
The serial number came from the Mattituck overhaul engine log entry along with Nitride cylinder info. This overhaul was done in NY before Mattituck closed. Hoping if I ever want more info I can get it from corporate in AL.