Anyone who wants the good oil on Muncie 4-speed gearboxes, or high performance manual gear boxes in general, can do no better than Mr Muncie himself: Paul Canglialosi.
Paul has been involved with rebuilding, manufacturing replacement parts and selling completely new replacement 4-speed Muncies since 1980.
I have both of his books: "Muncie 4-Speed Transmissions: How to Rebuild and Modify" [2014] and "How to Rebuild and Modify High-Performance Manual Transmissions" [2010].
Both are very well written, with a mine of information (historical and technical) and good clear photos.
Paul also has a YouTube Channel:
https://www.youtube.com/user/GearWorldTVand a website:
http://www.5speeds.com/about.html
