What Replaces A 87-011279-01B? 87-011751-01E?

The S drive had part number 87-011279-01B on its label.
This was the label on the side of the drive that shows the current dipswitch settings.
The front of the drive on the bottom would have S DRIVE and was 6Amp drive. The part number for the drive was S6-DRIVE.

What should I replace my S Drive with? (S3 Drive, S6 Drive, S8 Drive)

The SX drive had a part number 87-011751-01E on its label.
This was the label on the side of the drive that shows the current and address dipswitch settings.
The front of the drive on the bottom would have SX and was 6Amp drive. The part number for the drive was SX6-DRIVE.

What replaces a SX drive?