That's a Selway bolt-on. They're still being made.
The one in the photo is their side mount option - I believe their current side mount offering is the same connections / extension length but are now exposed pieces (i.e. the extension isn't clad in leather like the ones in the photo). The option is still available on their website for the side mount (attaches to bushings in the side of the riser like shown in the photo you posted.)
here ya gohttps://thunderhornmfg.com/collections/boas/products/two-point-take-down
Quote from: Kirkll on August 04, 2023, 01:13:25 PMhere ya gohttps://thunderhornmfg.com/collections/boas/products/two-point-take-downThanks Kirk. I emailed them earlier and am waiting for a reply as to whether they have extensions.
Take a look at the Marksman Quivers bolt down. Available with setback brackets which can be mounted at any angle desired.