just a quick thought, is the kickdown linkage adjusted properly? I had this problem on my 727 for a few years, I finally adjusted the kickdown linkage and everything was fine. No damage to the tranny at all.
Incorrect. If there is ever any slippage, there is damage done. Period. End of story. Over and out. Whether it's enough damage to make a difference will remain to be seen, but anytime clutches slip, material IS removed = damage.