I found this cool and rare brochure for the ill-fated Sierra Dana 20 overdrive on eBay. It’s printed on 8.5″x11″ paper, so the marketing budget must have been tight (as I understand it, working capital was an early issue, which played a part in the demise of the company). A few years ago there was a post of an article that also highlighted this rare overdrive.
The following instructions and schematics were tucked inside the brochure above: