1988 Deville English/Metric Readout

My 1988 Deville recently was serviced. The mechanic installed a new thermostat and replaced the hoses. Upon completion, I noticed the digital readouts for the gas and temperature is displayed in metric units. The owners manual states there should be a E/M switch to the left of the odometer digits, but there is not. I brought it back to the mechanic and he could not figure this out as well. How do I get the readout back to English???

In addition, does anyone know the proper thermostat for this car. A 160 or a 190?

Thank you

I used to have an 88 deville and I cant answer your questions but I wanted to say that it was a great car. Sorry.

I assume you have the digital dash; english/metric button should be just above the left turn signal indicator.