As mentioned in the previous picture, the Lionel Rectifier shell didn't seem to fit the Williams GP9 chassis properly, in that the rear flywheel was scraping against the sides of the shell.

Turns out that it would be scraping the former GP9 shell as well, if not for a clever little kludge on Williams' part. See that little brace in the shell? That spreads the edges apart subtlely, just enough to clear the flywheel. When I installed a little brace (made of strip basswood) into the Lionel rectifier shell, voila! No more scrape.

I'm a better scientist than I thought I was!

Photo © me.