Is it a double overdrive ?
Don't think so. Tom Beatty just made a casting to mate the T10 and the overdrive unit together. I've never seen one as long as this. At a guess, the eBay unit used the original mainshaft. It probably made the unit too long, so in the production version, he made a shortened mainshaft. I've got the production version and the center casting is 1/3 as long. That's why mine is so much shorter.
BTW, the OD is .72, or a 28% overdrive.
jack vines
