There's no conclusive evidence of Jerry using a Vox. The first known photos showing a wah are from approx 7/2/71, and its a ColorSound wah (which admittedly does look a lot like a Vox, esp when the top of the chrome rocker is hidden. Vox ones have a large "Vox" logo, Colorsound is wider and has a plain Chrome top at least viewed from a distance.
From mid-71 thru pics from 4/17 & 5/7/72 and 8/27/72 are all Colorsound. I don't know what he had in 73, but in the next known wah pic from 10/18/74 he has an all-black wah that looks more like a Crybaby or a Thomas Organ (maybe that is the same thing as a Vox?). In 76-78ish, the word is that he used a Mu-Tron wah, although he seems to have used it less and less, in addition to the newly added OctDiv and the III, and most consistently for GSET, eventually switching to envelope-only or envelope + phase for that song.
Check out the Teese/ Real McCoy wahs. He's got the RMC-1,2 & 3 and the Picture and Wizard Wahs. I've only gotten to play on an RMC-3 for a lil bit but it was niiiiiice. Just as nice as my 70's Thomas Organ Crybaby!
"There, in huge black letters, was 'The Grateful Dead'. It just... cancelled my mind out."-Garcia