Engine side mount
Mitsubishi mounted their transverse engines on either the left hand or right hand side of the engine bay.
Some Mitsubishi engines such as the 6G7x family and Sirius family were available as both left and right mounted engines and the Sirius in particular was difficult to convert from one to the other as there were different cylinder heads (so the exhaust remained at the front of the engine).
Right hand mount
With Magnas right hand mounted engines were used in the First generation and Second generation with the Astron II and 12 valve V6. Right mounted engines spun in a direction opposite to the wheels and as such had to be reversed before the differential.
Left hand mount
The left hand mounted engine appeared on the Third generation Magna with the Sirius and 24 valve V6. The main reason for the change was to create simpler transaxles as the engine spun in the same direction as the wheels when travelling forward, removing the need for a reverse gear before the differential. The left hand mount seems to make no difference to vibration and torque steer levels.