I have had one of the aluminum drums with the steel sleeve for 15 years, and it looks like new every time I pull apart the trans, to check it out. As a matter of fact, my 2nd gear band has never failed, but on inspection, it sometimes looked dark with the stock drum, but since using the sleeved drum, I can still read the part number on the lining after 400 runs. I assume the stainless steel sleeve has a slightly different Coefficient of friction, and it works just right on the overlap of the shift.