According to Aircraft in Focus:

First flown in 1930, the Monocoupe Model 90 was a refinement of the 1927 Velie Monocoupe that had more power and a longer, wider fuselage. These changes transformed the Monocoupe from a puddle jumper into a high performance sport airplane. Monocoupe 90s were built until the end of Monocoupe’s production run along side the more powerful Monocoupe 110 series.

N170K
The oldest Monocoupe 90 that I know of surviving is serial 504 – the serials continue from the Velie Monocoupes, so this would be one of the very early Monocoupe 90s, built in 1929 or 1930 – owned by the Airpower Museum. N170K is no longer listed on the US civil registry and also does not appear on the Airpower Museum’s aircraft list, so it may be in storage as a restoration project.

Taken with a Sony RX-100 M3.