I would presume that if the US still has stock on the 683 adapter it will be sold out before offering the replacement. Simple economics. Costs wise the 683 was selling for @$243 and the 682 sells for @$130 up north here.
Since all I am looking for is an eject box/base to 'borrow' parts from, the 591 kit was a good candidate. After all there is no 6NF option for an e38. Minor bump in the road of modding.

Craig