clunking from rear

My 1996 Dodge Dakota has developed a clunking sound from the rear as i slow down to come to a stop. It's a 5-speed manual and 2WD. I don't hear the noise when the truck is in motion or it's just coasting at normal speeds. However, when I drop under 15 mph whether I'm in gear or not, I start to hear a "clunk...clunk...clunk" and as I slow down the clunking gets slower, sort of like "clunk...clunk....clunk.......clunk.............clu nk" until I come to a complete stop. I also hear a single "clunk" when I put the truck into first gear, reverse or 2nd gear. It does not happen when I shift or when I accelerate. I suspect a bad spider gear. The UV joints don't seem to be bad on the drive shaft. There isn't any play in them or the drive shaft at all. It is all nice and tight. I haven't taken off the differential cover yet because I would like a second opinion from someone who knows what exactly the problem is or has suffered from these symptoms before. Thanks in advance.

Put the truck on jack stands. Get under the truck and with the truck in neutral. Move the drive shaft both ways normally you can feel where the problem is located. They sell shims at the dealer about .010 should be plenty
I have had to try different sizes before. They come in a pack I still have some from my dakota. I assume it is a 2WD without positracton. Also move each wheel feeling for loosness.

Could be carrier bearings too and pull the cover off to make sure.If it has posi traction,put the addative in first and most parts stores sell it.