Rear brakes aren't any harder to do on these cars than any other. Might even be easier. Do one side at a time. If you forget how they go back together look at the other side or the pics on the first page of this thread.
As for rockauto drums go...It looks like they have only one drum left in stock that I'd trust is the correct one. The drums on these things fit 2014-2015 only. 2017 and newer use a larger drum and different shoes.
Rock auto shows 3 drums for 2015 but they say they fit 2014-2019. So who knows which application they're actually for, I wouldn't bother with those ones(centric brand).
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View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)