Eaton Fuller question, clunk on downgrade?

Have a 1994 Ford L9000 with L10 and 9 speed Eaton Fuller RTFX11609R. It has been making a noise for probably about a year. But very rarely. In 9th gear, on very rare occasions, maybe like 1 or 2 times a month, I would hear a very light clunk noise, maybe more of at tick noise. And 90% of the time it was on a downgrade when letting off the throttle a little. But in the last couple weeks, it has definitely started happening more often. So what it sounds like to me is the Hi/Lo splitter. It kind of makes a similar noise to that, sometimes less and sometimes more pronounced. It has also started doing it as I am cruising down the road anytime above 60. Sometimes it could happen like once every 5 minutes or so. So I was hoping for some thoughts of what this could be. And if you think it could be the splitter, is this an easy fix. I am not a tranny guy but I was told this could be accessed from the top of the tranny from inside threw the cab floor.

 

I have a while back but not recently so I will check the U joints. Previous there were no issues.
Yes, I am going to drain the differential, single axle, this coming weekend. Time for a PM anyway. I will see what I can find before I go digging into the tranny. I dont know my way around the tranny so I will have to have someone look at that I guess.
One other thing I should mention that just came to mind. It seems sometimes that when I let the clutch out that there is a slight hesitation before it goes. Like some slop somewhere. Very slight but it seems as though there might be some slop. Just not all the time if that makes any sense.