'04 Impala speedo from kph to mph?

Helping with a car that was bought with a kph speedo. So...

How do you swap the speedo from kph/kilometers to mph/miles?

I'm presuming that the speed and distance are stored in the engine ecu, displayed from PID's (such as with rpm, fuel level, coolant temp, etc). So if the speedo is replaced, does the pcm sense this? Or is there a switch that has to be set from metric to english? Or does the entire pcm have to be replaced with an english unit?

Thanks!

Is this analog or digital?

If analog, usually the speedometer has the mph numbers larger and the KM number, smaller.....driver information center has the ability to change it back and forth...

Is this analog or digital?

If analog, usually the speedometer has the mph numbers larger and the KM number, smaller.....driver information center has the ability to change it back and forth...
Analog. It looks like the numbers are silkscreened on. I've seen digital faux-analog IPs that are analog-shaped, yet can be flipped back/forth, and this doesn't appear to be one like that.

Three circle analog gauges, fuel / speedo / coolant. Speedo goes to 200kph in big white numbers, and 120mph in little grey numbers, by 20s. Below is the light green display, with icons for gear, and the total kilometers below that.

So they can see their speed in mph, if they zone in on the light grey numbers, yet if it's just a new mph IP and a (free) computer bit switch, they'd go through the effort.

I'm hoping it's just an IP swap. The gas gauge is in % and not liters, and believe the coolant is in % and not C. I was going to hook up an ODB-II CAN Bus reader, and see if it displays speed accurately in mph.