This model is actually pretty clean and might boolean into a single solid but even then it has way to much detail which will carry over into drawings etc. (Do you really need the fins and the vent coolling holes in the back, the text on the top?)
Most often supplier parts have WAY to much detail in them where all you need are the overall dimensions, shaft location/size and mounting locations.
For Assemblies like this I place them in an ASM and Create a new part in place.
I then model using Sync to create a simplified rep. (Sync Extrude, Boolean, replace face etc.)
to get what I want.
This works well for parts like this and also works when it is a true ASM. If you are running managed you can create a single part and check that in rather than checking in 100's of files (Perhaps) that make up the componet you really treat as a single part in your design.
Again, I don't try to "fix" the imported geometry which can take hours. I use this to make a new part that is a clean single solid. Taking a few minutes to do this can yield some nice results.
Hope this helps