Having recently consolidated to a single imaging scope, I no longer require this side-by-side setup.
The Losmandy D-style plate is 14" long, and the dual 8" saddle plates take Losmandy or Vixen style dovetail bars.
It's similar to the following from Bintel, but with the earlier style large knurled knobs for tightening.
https://www.bintel.com.au/product/lo...ovetail-plate/
$280 plus postage.
Please send a PM if interested.