shackles and drive shaft angle?

Quick question. Do longer leaf spring shackles at the rear improve drive shaft angle or make it worse. I want to raise it about an 1 1/2 more at the back : on top of the already 4''. I would think that longer shackles would point the rear diff up a little. Wasnt sure.

Yes, your pinion will point a little higher...but the distance from the transfer case will increase also a little.

will this cancel each other out? say an 1 1/2 lift. (differencial angle and increased distance to transfer case?) I dropped the t case 1'' alredy and have 4'' lift right now. Don't want to have to get a sye.

I am not sure about improving the pinion angle but according to the instructions for my daystar shackles they won't make it any worse.