The battery is 5mm thick and 127X118mm The side that is 118 could go a bit bigger to 123mm You could also go 1mm thicker but the battery would be touching the back case then.
Any leads on this would be great... I would love to have the option to do this myself so I wouldn't have to bring my Gtab back to stock and ship it to Viewsonic.
Is there someone out there willing to open their tab and get numbers off the battery to research this?