Rockauto shows 2 possible computers for an 89 W100 with automatic (I assumed you had a 318, if not then this does not apply)

One for California emissions, one for federal emissions.

It's a bit more complicated if you have the V6. One fed, two Cal, depending on date of manufacture of vehicle.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.