It looks like this Part has been superseded by LEGO Part 98302 Engine, Smooth Small, 1 x 2 Side Plate with Axle Holders and Slot.
Click on a colored part below to see the Sets and MOCs that use part 3475b Engine - Smooth, Small 1 x 2 Side Plate [With Axle Holders] in that color. You can find an overview of all LEGO Colors here.
If a color is missing, it probably needs to be added to a Set Inventory.
This part has been used by MOCs in the following colors but not officially released.