Redoing the Brakes... but the rear's are locking up on hard braking

[sircrunch]

I've been working on my truck brakes for quite a while now. It originally had manual brakes. I upgraded to power brakes. Soon after upgrading I noticed a few days later my brakes were starting to fade. It got so bad after a few days I realized only one wheel was braking, because the right rear tire would lock up and slide.

I have replaced the following:

Rear Drums
Rear Shoes
Rear Wheel Cylinders
Rear Spring Kit
Rear rubber brake line
Rear stainless axle brake lines
Front Rubber Lines
Master Cyl
Booster

I simply inspected the front disc brake pads and they looked like they had plenty of material left.

I bled all 4 wheels once finished.

Now that I have done all that work, the back wheels are locking up under hard braking. The good thing is that its both back wheels instead of the one before... But, this locking up tells me the fronts aren't working like they should. The bleeding process went well, I got a good hard stream from all 4 corners.

What should I do at this point?

Also, for bonus points, what do I need to replace to keep grease from splashing outward from the hub all over my front wheels?