There are two sizes of calipers listed for my little red wagon, an ATE 38 or an ATE 40, but neither of these numbers appear on the caliper. The only thing I can make out is "52" and "G-9". I assume the 38 or 40 refers to the size in millimeters, perhaps the piston diameter. Can anyone identify mine, or tell me how to figure out which calipers to buy, without actually taking them off? I'll start using WD 40 or Liquid Wrench, for two weeks, before I try to tale the brake lines off, but I still need to order the calipers, first. None in stock at NAPA.

Thanks for any help you can give!