[Grumpy old man]

I had mine totally rebuilt using a (72) 661 main case with the 1" counter shaft and drilled and tapped for the fill/drain magnetic plugs from Paul and a number of other upgrades from his videos , I used the drivers side speedo tail shaft and even used the (Joe Gibbs) Driven gear oil in the trans and rear posi diff (locally $30.00 a quart Summit about $10.00) M-22 geared with the red speedo gear using 29" 255-70-15 tires should keep my speedometer correct .

https://www.youtube.com/watch?v=HUBFMwO8Qc0

https://www.youtube.com/watch?v=Z7NpsMZ9pBQ

I watched all of Paul's gearboxvideo's on the Muncie's , I mean hey the guy wrote the book on Munice's and for what it all costs to use an old school 4 speed I'd rather only do it once ( I hope)