Tom them trannys depend on SLINGING oil around. Overfilling them will cause the gears to run in oil like a propeller. I would never overfil a tranny! Trust me you are doing it a disservice. Think of how many millions of them are running around and a bunch of them are LOW on lubricant... They still work fine. The hard shifting can be temporary, caused by new bearings/gears or whatever. I would take the fil plug back out and let her drain to the hole again.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

professional bovine relocation specialist