If your talking about a junkyard transmission swap, and having it done I would think yes. If you are talking about a mercedes remanufactured transmission swapped and ready to go definitely not. I would think you would want to be sure of what is wrong before you replace it. You could do some testing like check it for vacuum at the transmission or not? Also, try to determine where the leak is. If it's the pan that's leaking etc. The transmission is an expensive repair on them, and it's best to do it right! Just an oil and filter change at a shop on them is probably 150 to 200.