I do not read that the OP bought or tried a new SLK pump. He only states that he has the part number and was wondering if the CLK pump would work as it is less expensive.
The extra outlets on the pump of the CLK is for releasing the trunk. The CLK key FOB also has an extra button for the trunk release so there is a difference in the electronics somewhere. The Crossfire has no truck release.
My question would be why does the OP think replacing the locking/unlocking pump has anything to do with his ESP/BAS warning light and the spoiler deploying?