More interesting stuff from needlebar referring to the #9, however this lists it having a top leaf tension, while yours has the front like the one in the picture link above - so it must have come both ways.
Whilst the No. 8 was a hand machine, this model was primarily a treadle. It has an automatic rack and pinion bobbin winder and a distinctive top leaf tension and this version uses a conventional bobbin and shuttle.
It seems likely that this machine was known as the Iowa when sold by Sears Roebuck. The American Sewing Machine Company made the Iowa No. 1, No. 2, No. 3 and No. 4.
However, National also made an Iowa No. 1 & No. 3. Davis made a No. 2 and Standard made a No. 4.