Well I looked at that Thread and checked out my truck and determined that was not my problem.

BUT that Thread got me thinking as I stared at the back of my truck - just seemed that the back left tire/wheel was hanging down too much and I realized that both times I took measurements the truck was in the same position in the garage....

So just like most of the people that worked on my house, I figured the slab contracters probably did not pour a level(left to right, I know it needs to slope front to back for drainage) slab. So I moved the truck out to the best(level looking) area of concrete outside of the garage and remeasured.

Anyway my left and right measurements are all within about 1/8" now! I think there is a small "valley" in my garage where the back left tire sits.

Looks like my rake is real close to 2 3/4", so I will use that as I decide on my coilover mod.

Thanks for the responses, feel much better now!