The subject of a differential vent for a Model A with a Mitchell overdrive installed has been discussed on the barn a number of times. The attached document is further to that discussion. I have also discussed the subject with Steve Mitchell. This document is posted on the web site of the Santa Anita A's Model A Ford Club of Arcadia, California
santaanitaas.org
https://www.santaanitaas.org/wp-cont...ntial-Vent.pdf
Tom Endy