well, about 50k into this unit, it gave up the ghost. Installed a back-up unit i had, self bleeding, for the ast 2yrs. That one i wasnt confident with, so in the meantime, i ordered p/n PF9021 off ebay. It was a Perfection system, the same Advance Auto sells..(same p/n too). Well, it arrived today and sure enough, the units' ALL ALUMINUM.....YA BUDDY! BTW, $98.00std