Helping a friend who has two bare frames he wants to build. Both have the more modern tubular shock mounts which means they are 1950 or newer. The difference is the E-brake cross shaft and how the e-brake levers that pull the e-brake cables are mounted to the shaft. One has small teeth which allows you to orient the lever in two or three different positions on the cross shaft. The other has two flats which only allows one position for the lever. This second one was just purchased as a 1953 chassis. I'd like to find out when this change took place to give me a better idea of the year of the other chassis.