Do you really mean "VXIII"?
Or, "Vari X III"?
The Vari X III is the oldest, with the VX III being one generation newer, and the VX 3 being the newest series.
I bought a used Vari X III, 3.5-10X40 AO, and sent it in to Leupold for inspection because the ocular lens housing looked bent. The original owner told me he had bounced it around inside a hard case carried on the handlebars of his ATV.
Leupold determined the innards were too badly damaged to be fixed: it being out of production (no new ones available), they offered me a new VX 3!
.
I paid $250 for the Vari X III, and they gave me the VX 3 at no cost!(a $430 scope - 2.5-8X36 model)
Gotta LOVE Leupold customer service.