I bought a pair of reconditioned brake calipers from the local Advanced Auto Parts store. They are reconditioned Kelsey Hayes original cores for my 71 Charger R/T. They come in a nice zinc coating with the hardware for $24.00 a piece. I put them on the car,after coating them with high clear to preserve the nice zinc finish and prevent them from rusting. I always put antisieze compound on the threads of the mounting pins and bleeder screws. So I grab a 3/8 inch wrench to remove the bleeder screw on the first caliper and treat the threads. I go over to do the same thing to the second caliper,and my 3/8 inch wrench doesn't fit! The damn bleeder screw was 10 millimeter! Metric screws on an American car! Now I need to use two different wrenches to bleed the brakes!