My rear brakes are real touchy and been that way for a while. The Hydro boost started leaking so replaced and everything was good for 2 days and now back to locking up right rear. I ordered a divider valve today just because it was cheap enough to throw at it. No codes or anything so what do you think? 

Rear drum or disc brakes?

 

Drum brakes could be a rust or corrosion issue in the drum. I had this same problem where it would lock up the rear tires really easy on my 1996 Dodge Ram 1500. The thin layer of rust would be just enough to get the brake shoes to be grabby. Might just pull the drums and inspect the insides for rust or broken parts. 

 

 

Had that happen on a work van with rear drum brakes.  It turned out to be a sticking brake wheel cylinder on the right rear.

Drum brakes, they have hit so hard that it brakes keepers and springs. Hasn't done that in a while, 

 

Time to grease those brake pads... (You know I'm just joking right?!) 

 

Seriously, I've got to ask what type of brake shoes are you using? If you are using too aggressive of a shoe material it might be creating a grabby condition like some of the clutches can. Might consider changing shoes out for some baseline generics if you are using any kind of premium brake shoes. 

I hate drums, gave me a headache everytime my neighbor played them