What must be prevented when removing the half shafts on certain transaxles?

When removing the half shafts on certain transaxles, it is essential to prevent the differential case from dropping into the transaxle housing. This is critical because if the differential case falls out of position, it can result in significant damage to the internal components of the transaxle, making repairs much more complex and costly.

The differential case holds the gears that allow wheel speed variation during turns, and it is crucial for maintaining proper operation of the transaxle. Ensuring that it remains secured during the removal process helps maintain the alignment and integrity of these components.

In contrast, while the other options involve important components within the transaxle, they don't typically represent the primary concern during the removal of half shafts. For example, drive pinion and differential drive gear timing or the position of the pinion shaft can be addressed in specific service procedures, but the risk of the differential case dropping is a more immediate and common danger in this context.