Originally Posted by T-Mar

My leading candidate would be Bridgestone 400. The frame was an unspecified triple butted CrMo main triangle and this would be consistent with Ishiwata EX. The stays and forks were hi-tensile steel. The frame features are also consistent for a Bridgestone 400, with the exception of a derailleur hanger and dropout eyelets, which as discussed earlier, were probably removed. Even the steel headset, which is the component most likely to be OEM, is correct.