1991 Johnson/Evinrude Models "EI" 40 thru 55 Service Manual, Page 224Get this manual
Driveshaft Shimming Using Tool PIN 393185 The driveshaft pinion is precisely meshed with the forward and reverse gears by the use of shim or shims between the driveshaft bearing housing and thrust washerWhen installing new thrust bearing or washer, bearing housing, pinion, or driveshaft, it is necessary to gauge and select the proper shims to restore factory clearanceGauge bars are precision made and should be handled carefullyThe length of each gauge is stamped near the part number, and this dimension can be used to measure the gauge to confirm accuracyThis dimension is .020 in (0,508 mm) shorter than the actual shimmed length of the driveshaft