For lifting, you want to add a taller block under the leaf springs and on top of the axle. No need to do anything with the shackles. And you will need longer u-bolts as well.

Unless you are actually wanting to lower the truck and not lift it.

 

You can get 1" lift shackles for the factory hanger but that is as short as you can physically go and still allow enough room for the leaf spring eye. If you want to go higher than 1" you would have to do a taller block like Neal said above OR do an aftermarket flip hanger which will raise you 1" or 2" depending on the style and placement and then you can add a longer shackle to get you another 1" or so to make it 2-3" total. The easiest route is to do the 1" lift shackle and if thats not enough do a taller block. Cutting off the factory riveted hanger is a PITA....

 

There are shackles you can buy that will allow you go up a few inches. They are like adjustable hangers pretty much..

Blocks should never be taller than 3"...you'll get axle wrap and an overall crappy ride. I have 6" blocks and they suck...

 

Thank you all for your replies, all very useful.
I should've mentioned this before, for which I apologize... but I'm running a 7.5 inch lift kit, on the rear I'm using the 7 inch block that came with the kit, but my problem is that on the front I was previously running Rancho quick lift shocks which gave it at least a couple inches more than that 7.5 inch kit on the front, causing a slight squat which I HATE... i'm looking to raise the rear at least 1.5 inches to see if I can level it out. Any suggestions?

 

Whoa....what sort of angles are your front suspension looking like? I thought the 7.5 lift was already stretched suspension and add another 2" on that would be really bad. Got any pictures of what the CV axle and control arms look like?

 

Your really at the point where you should get lift springs for the rear. That is an enormous lift block to run. But, if you want to keep your current setup the easiest thing do do would be to add 1" lift shackles in the rear (1" shorter than stock shackle) OR, maybe the better thing to do is lower the front 1" by removing or replacing the strut spacer (assuming one was used as part of the kit).

 

I don't think my CVs are angled too bad, doesn't ride like factory but it isn't that bad either. Uploaded pictures.

 

That is definitely a 4-5" lift stretched to 7.5" you are already at the limit of down travel on the control arms and steep angled on your axles.

I like the painted springs though! but i am biased! haha

Does not look like you can do much to lower the front other than ditching the Rancho quick lift shocks and getting standard height ones.

 

I'd do blocks before shackles any day.
Shorter shackles = harder suspension. The articulation of the shackle allows for more room for the leaf spring to flex.
Way longer shackles over factory = sloppy rear end, as the shackles will flex sideways more with longer length.

Suspension blocks get poo-pooed all the time, but when kept sane, they are fine for a street truck.
The problem is when VERY tall blocks are used to the point that under torsional load, the driveshaft turning gets leverage and starts to twist the entire axle housing upward or downward.
This leads to a pinion angle getting out of whack = u-joint dies and/or pinion bearing dies.
Worse is the u-bolts starts to stretch and everything gets loose.

Also note that good blocks have a slight trapezoid shape, being smaller on the front edge.
This helps rotate the default pinion angle to point more at the driveshaft and prevent vibration (or worse).

 

@CT2500HD thanks for the valuable info. Taken into consideration... convinced that I'm not gonna mess with the leaf spring shackles...I'll just leave the lift block that came with the lift...

 

how do you guys feel about removing the 6.5" strut spacer that came with the lift kit and replacing it with a 3" spacer and adding a 2.5" block spacer under shocks...??
Like I posted before, I need to lower the front and get rid of that squat look due to my Rancho Quick Lift Shocks

 

Or drop to a 4" spacer and be done. It looks about like a 4" lift stretched out anyway. So a 4" spacer would get your angles flat again and get rid of the nose up rake.

 

If you can find a shorter spacer that will lower the front. But the length of the spacer vs the amount of lift of the truck is not a one to one relation.