The wrx DS has some give to it. It uses a flex joint instead of a full yoke. The STi DS has a full yoke in it, so there is no play in length with that. I've been using a 6 speed the whole time, both before the swap and after... Now I'm just using a JDM 6 speed instead of a USDM 04 STi 6 speed. Same lengths. Just now I don't have dccd where the trans before did. You can keep the wrx DS and use the 6 speed. I cannot fully say how this will work with an R180 though, as I tried both shafts in with an R160 and it worked, but chose to go straight to STi DS for the R180. I'll try to post some pics later this week for you if I can get all the parts next to each other. Would rather not pull the DS again though. Can show both under the car.