Are the gear ratios of a prewar A single box the same as a post war box? Are all the gears interchangeable? How many loose rollers are there fitted to the selector shaft? With a full compliment of 3/16" rollers, the selector shaft will not enter the bearing outer bush. Should there be either one or two less than the full amount. Should the rollers be 4.5mm dia. instead of 3/16"?