my dad just did his calipers last spring on his 66 427 roadster bought the p.e. o-ring kit and the where really helpfull on the phone and my dads calipers needed some more grinding in bores because the pistons where hitting so they told him to ship them to them and they grinded them and assembled them very reasonable so far no problems and my dad is happy with them. i have not delt with them yet but i was going to try them first but will have to wait till i dig myself out of the holiday c.c. bills and do my 75