what happens to a 727 [and converter] if one switches to the [any old brand] type F from a synthetic fluid ? i have never had a failure from using type F in any 727 or 904, [and even using dex 3 in the later front drives that are supposed to use +4] but i have absolutely no experience with synthetics.
just a drain and refill, not a fresh rebuild, and there will still be some synthetic that won't be totally drained.