1994, Ford Ranger. 2x4 rear wheel drive... drum brakes in the rear. I have discovered that the "thud, thud, thud" is brake related. I can only hear it when I am nearing a stop, because it isn't loud enough or violent enough to feel or hear when braking at higher speeds.

However, when I am coming to a stop (like, a red light or a stop sign) it sounds like (thud... thud... thud) with each full wheel rotation when the brakes are replied. It sounds like it is coming from the rear of my truck.

I took the tires off and looked inside the drums. The breaks have a good amount of pad left, and the drums are smooth inside.

What could be causing this "thud" sound when I am applying the brakes?
If it matters, I should note that this has been happening for a long time now... probably a couple years.

I replaced the FRONT pads about 1 year ago, along with roters.
Also, I just had the entire clutch assembly replaced a few months ago, along with the slave and master cylinder.

This "thud" sound when brakes are applied has been happening long before that.