yeah if u do a sup lift then u will probly need the diff drop. If not it could tear up the cv's over time. my fleabay kit came with the drops.
Also if u do get a lift go and by u some screw in pipe clamps and replace the ones on the outer cv boots cause like with mine i didnt know about it and i did the lift and i lost lots of greese from the boots and also made a mess under the truck so i replace then with new clamps but only after it was to late. If i would had done it at first it could had all been avoided.