I don't haul anything heavy, and I want to get the rear end more level with the front; my rear end is a lot higher, and the Bilstein shocks look like they were put on in 2001. What is the best way to level out the ride height without having to redo the entire suspension?

 

I'm guessing you have a four wheel drive? You could allways crank up the t-bars in the front a little to get it level and then get an alignment.
I think this is the first time I have heard of this problem, usually blazers sag in the rear.
Earlier this year I changed out my factory 12 year old bilsteins. . . for about a week. They were much better than the new ranchos (ya I know) that I put on it.

 

Mine sags in the front as well. About 1 1/2 inch on the pass side 1 3/4 on the driver. Gonna try the T-Bars when i get around to it.

 

I will have to try cranking them up, thanks!