While working at the bridge, I recorded a 72 diurnal increase from 8 to 80 degrees on 10/23/2003, but temperatures taken at the river, and because of cold air pooling it is kind of cheating. At the official weather station, the range was 18 to 80, so only 62 degrees on that day (which is still pretty large).
At the official weather station, since I lived here the temperature has gone from 32 to 95 in a day, a 63 degree rise. At the house, 65 degrees is probably the most I have seen (32 to 97).
Just west of us though, Maybell has us beat. On 2/1/1985 the temperature rose from -61 to 6, a rise of 67 degrees. This was matched the next day when the temperature rose from -52 to 15.
This January, where I live the temperature went from -43 to +43 in two days, but that's not quite as impressive as some of the changes that have happened in eastern Montana.
Although not populated, Peter Sinks has some of the largest diurnal changes (possibly even the largest), even though there are no Chinooks there.
On 2/10/2010 the temperature went from -46 to 28, a 74 degree rise, comparable to the one at Deeth.
More recently, on 1/7/2017 Peter Sinks went from -42 to 23, but the impressive part was that 50 degrees of the change actually happened in two hours (which is pretty impressive considering that there are no Chinook winds there):
My guess is now that Peter Sinks has a permanent weather station (since 2010), it will probably break the Deeth record eventually, unless it has already and no one happened to notice.