http://www.ebay.com.au/itm/Pinball-rails-/181146905184?pt=AU_CoinOp&hash=item2a2d326a60&_uhb=1

Here's a set of sys3 rails I've got on the bay at the moment.

Pretty sure my stargate has 31 inch legs.
It's easy to tell as the bolt holes are up a lot higher on the front of the cabinet than standard.