Honestly I dont get the diff drop. Seems like its only so old cv boots dont leak, just replace boots if they leak.
(I did buy the drop when I ordered my lift but choose to wait and watch CV, never even opened package)
I have newer Cv and I installed OME coils and didnt use the drop. Ive put car through the limits and I dont have any problems. every tough road in death valley didnt stop me!