I'm guessing a Mazda 3 would have 3 engine mounts but rockauto only sells the front right mount. No stocks for the front left or any rear mounts. The dealership (upon getting diagnostics done) suggested to replace engine mount #3 and the dog bone mount. I'm sure there's 3 engine mounts so might as well replace all. They also suggested to replace the worn out transmission mount. Rockauto sells the left mount, but doesn't state what the other transmission mounts they sell, if it's either for a right or a left (I'll contact the manufacturer later).
2015 Mazda3
2015 Mazda3