Hi, I had the viscous coupling replaced on a lucida as well recently. If you are only replacing the viscous coupling with the fan, the answer is yes, you can replace the unit without having to remove the prop shaft. What you would have to do is remove the four phillips screws that hold the plastic radiator top air duct. then undo the 4 bolts retaining the viscous to the prop shaft. the whole unit will come out and then once it is out you can undo the plastic fan and replace the viscous with a new one. it is a bit tricky to get the whole unit out once you have undone the 4 nuts but it does come out from the top itself. putting it back is just reverse.