Do you have a CV driveshaft? If no CV driveshaft, and no SYE, you need to make your pinion angle parallel to the Transfer case output (the slip yoke). Make sure your differential u-joint doesn't bind. If it does, you need an SYE and CV driveshaft.
Once you get the CV driveshaft and SYE, adjust your pinion angle to match (or be ~1 degree less than) your driveshaft angle.