I just dumped same into the FAQ!
How to determine auto transmission type in a 8th gen
1. Cars with the 4-speed have an "Overdrive" button on the shifter, just below the big button. Those with 3-speed don't.
2. For the highly technical, 4-speed transmission takes two connectors from the engine wire harness. One rounded rectangular, and one with 3 wires. 3-speed takes just one, and it looks like a house, for lack of a better words.
3. Look at the "TM" code on your car's certification label, by the driver side door pillar. 3-speed is A131L, 4-speed is A245E. (and just for completeness, 5-speed manual is C59.)
You cannot tell transmission type just from the VIN.