In relation to the English production of Dragon Ball Z, we've seen the aforementioned "Westwood Studios English Dub" preserved in superb quality thanks to the tireless efforts of folks like DBZImran and everyone else involved that had either sent in or transferred their own VHS tapes recorded from various networks in the UK/Canada in the early 2000s. In addition, thanks to Arian, we've also seen the original syndicated version of The Tree of Might resurface online; a film that was chopped up into three episodes complete with their own unique narrated recaps and next episode previews that never made it to any of the home video releases. VegettoEX did a quick write-up here on Kanzenshuu proving that Episode 51 of FUNimation's English dub of Dragon Ball Z did in fact have an alternate title that was only seen during it's initial broadcast and never again- a fact that fans were skeptical of even just weeks after it had originally aired in Mid-1998. All of this is to say that in the past two years, nearly everything that was created relating to the Western/English-dubbed versions of Dragon Ball has been accounted for and preserved in some form or another online.
It appears that the last great mystery surrounding the English production of Dragon Ball Z is the little-known test dub of Dragon Ball Z: Dead Zone that was recorded sometime in either 1995 or early 1996. VegettoEX did a comprehensive write-up on this whilst documenting all that's known regarding the original 1995 pilot of Dragon Ball: Curse of the Blood Rubie.
The most puzzling thing about the "Vendar" dub of Dragon Ball Z: Dead Zone is that there appears to be zero tangible evidence of its existence. While brief clips of Dragon Ball: Curse of the Blood Rubie as well as the physical tape itself were seen in the special features included on the Season Set Blu-rays for Dragon Ball Z, the same cannot be said for the test dub of Dragon Ball Z. In addition, five copies of Dragon Ball: Curse of the Blood Rubie are known to exist, with a few copies ending up in the hands of collectors. Again, none of this is true for Dragon Ball Z's pilot. The only thing we have to go off of regarding the contents of the tape come from an old post to a newsgroup from Matthew Sommer in 1996. It's not even known what the title of the film is- whether it had remained the same or was simply titled, "Dragon Ball Z: The Movie" is anyone's guess, as according to Matthew Sommer's post, the actual "Dead Zone" was originally renamed "Death Zone Vortex" in the pilot.
It's easy for me to infer that the intro that appears on the original North American Pioneer VHS/DVD for "Dragon Ball Z: Volume 1 - Arrival" comes directly from the pilot. I believe this due to the fact that it highlights clips from The Dead Zone, uses a newly written score from Peter Berring and narration from Jim Conrad (both previously heard in FUNimation's initial attempt at Dragon Ball), and an odd mix of Masako Nozawa's original Goku performance juxtaposed with the grunts of an English dub actor for Goku that, to my ear, does not sound like Ian Corlett. It makes sense that these would all be used in the interim, much like how a lot of the Harmony Gold-isms were kept around for Dragon Ball: Curse of the Blood Rubie. Even as a kid, the intro struck me as more of a sales pitch than an introduction to a new show, and as an adult I find it hard to believe that FUNimation would've solely commissioned Peter Berring and Jim Conrad to figuratively pass the torch to their successors in Dragon Ball Z (Ron Wasserman and Doc Harris respectively).
Matthew's descriptions of how the characters sound are interesting, though. It seems as though most of the cast from FUNimation's previous effort in Dragon Ball still retained their roles going into Z. He also mentioned that Krillin sounded "dorky" which is a pretty apt description of how most would agree Terry Klassen's performance as Krillin would go on to sound. Oddly, Matthew mentions that he believes Ted Cole, the voice of Yamcha, was playing the adult Goku seen in the pilot dub. Ian Corlett has gone on record saying that he, Terry Klassen, and Barry Watson were in charge of the casting process for Dragon Ball Z, and as such he effectively cast himself in the role of Goku. He was previously heavily involved with the "re-versioning" process of Dragon Ball, contributing his vocal and writing talents to all thirteen episodes of the original production. With that in mind, one could argue either way as to who may have played Goku, but without having seen it, it's impossible to tell. I do find the prospect of somebody else potentially being the first English voice of an adult Goku rather exciting.
Considering how much has been unearthed in recent years regarding thought-to-be-lost media in the Dragon Ball Z franchise, I have hope that one day this dub will find its way in the hands of someone kind enough to share it online. In my (mostly) vain attempts at trying to find anything related to the dub beyond what's been covered here on Kanzenshuu, I did come across something pretty intriguing that I haven't seen be discussed anywhere else.
The Dragon Ball Z Ani-Mayhem Card Game by Pioneer was the first card game in North America the featured the Dragon Ball Z license starting all the way back in 1996. A collector named Ryan Richards owns the web domain for Ani-Mayhem and has digitized the vast majority of the cards that were released in that series. Similarly to the Bandai figures of the era, a lot of the cards feature early dub names that ended up changing by the time the characters were introduced in the show (i.e. Freeza instead of Frieza). The site also contains a section documenting pre-production cards that are in black and white. Although most reflect the final product with very little difference between the two, the one for "Garlic Jr.'s Palace" was renamed prior to release.

I believe this puts any doubt to rest regarding the validity of Matthew Sommer's post, if there was any to begin with! Like I said, here's hoping that one day it'll turn up online, through official channels (maybe FUNimation's Crunchyroll's 30th anniversary next year?) or otherwise!

