I have recently upgraded my 2001 Tundra front brake calipers and as a result I have the original calipers left over. The brakes were working well when I removed them. I had upgraded rotors at about 14,000 miles. I wanted to do the recommended caliper upgrade also. They have 34,000 miles on them and the pads have about 20,000 miles on them. I have been told the Tundra original calipers can be used to upgrade 4runner sytems. If anyone is interested in these calipers w/pads PM me.