Probably was the last part you changed out. Especially if you heard someone else had the same issue more or less. May be a break in noise of some sort that will go away.

Although I thought the linkage was just fluid driven. But you see clutch plates so it is a little more complex and could easily make noise. Did you check the fluid level? I thought I heard somewhere that they are to be stored in a certain position until installed but not sure. Dry friction plates only partially engaged would make noise for example. Was the outside of the case bone dry when you got it? I suspect you will have to verify there is adequate fluid in there.

Strange set up. Low on fluid and they slip excessively was my understanding. So they perhaps incorporate a combination drive coupling. Partial hydrostatic in combination with friction clutches. Although I have never had one apart to see.