1911 accessory rail ID help

I'm looking for pictures/info on an older version of an add-on accessory rail for 1911 pistols. Unlike the newer offerings (Caspian/Dawson etc) this was a rail that was U-shaped in cross-section and the sides extended up to the top of the dust cover on the frame, essentially meeting the slide.

It may also have been secured by screws on either side of the dust cover, rather than at the bottom as with the newer rails.

Can anyone ID the manufacturer, or provide pictures? I'm considering trying to find one for a potential project.

Thanks for any help.

Anyone?

One last try. Bueller?

Aha! Many thanks.