Rebuilding a 700R4 in 4x4 for towing
You will benefit from a 3-4 clutch kit that allows you to install more than 6 clutchs in the drum. I'm curious about the input you may have gotten, which influenced your decision about the 3-4 setup.
I am impressed with the amount of research and time you have invested in this.
One other thing,the checkball capsule[in the case,servo area],we remove those capsules and plug the hole.We use a GM anchor pin cup plug.
If the ball does not seat in the capsule,from any type of debris,it will be a leak, and disturbs the band release clutch apply function.
This can take out the 2-4 band and or the 3-4 clutchs....It has happened to me.