Questions on overdrives come up here frequently. This article was linked on another site and I found it informative mainly on the uses and history of the BW units in general. I’m not sure it’s all correct, but it’s pretty good. So I’m posting the link here for those who might be able to use it or those just curious. It’s not a replacement for the original service manual, but still useful.
http://www.fordification.com/tech/overdrive.htm