[Gigakaiser]

SOLVED:

Here is the solution if anyone else needs it:

-After you create the assembly (in my case the left drivetrain) create a new PART.

-Go to manage->insert->derive and select your assembly. There are extra options that will change depending on your needs in this window.

-Go to the options tab

-select "mirror"

Now you have a second "assembly" to place in your final robot assembly. Since it is derived from the first (left drivetrain) changing the first assembly will update both. This is very useful, especially for those designing symetrical components.