Not to keep beating a dead horse here but I was going back over this thread and realized that I didn't mention a couple of very basic things----

WHEN you have a braking problem, the problem is probably on the opposite end of the car not doing its share of the load---in this case ( and many especially with big and littles) the front brakes aren't doing there share of the stopping--and the rears then lock up early---

In drum brakes this can be as simple as having the shoes on backwards or the backingplates on the wrong side---there is a primary shoe and seconary shoe---they go on a certain way--and since drum brakes are self energising the side of the car the backing plate on might make a differance.