i have an 87 toyota pickup that has the 63s on the back and SAS on the front, the back of my truck sags, it already has 2 inch lift blocks on the back. can i get taller lift blocks or add a leaf to raise it so its level

 

Big blocks are a bad idea. You'll have a lot of axle wrapage. Best thing to do it get leafs to match your front end. Are you running stock leafs in the rear? How much sag do you have? An Add-a-Leaf may work but I'd consider getting lift springs for the rear to match the front.

 

pics would help.

what shackles do you have?

i'm thinking ditch the blocks, like stated above, and run some 12" shackles that mount (welded) above the frame for max articulation.

chevy 63's are supposed to lift about four inches, how much lift do you have on the front?

 

Yes.

 

My truck rides much better after ditching the blocks for add a leaves. Plus if you did the 63 swap and SAS you are probably wheeling, and blocks greatly limit your travel compared to leaf packs that sit directly on the axle. As said above the 63" swap, when done correctly, should bring you about 4" over stock. It would help if we knew how much your front end is lifted. If it's around 4" then you likely have some trashed 63s in back and the cheapest/easiest and probably best fix is to find some in better shape at a junk yard. Not hard to find and usually super cheap. Plus it would be more durable than the AAL which are a bit prone to stressing/breaking the original leaves, Afaik.