I don't remember specifically what your '46 transmission has for speedometer gears, but typically the driven gear, where the cable attaches, is held to the transmission case by bolt and clamp arrangement. Remove the bolt and clamp and pull the gear assembly out or the transmission case. The gear usually slides out, but it may be stuck. Depending on where the gear is located in the case, be ready to plug the opening or you may drain the oil from the transmission- all over you. If the cable attachment is above the transmission fill plug, you shouldn't lose any oil.
You should be able to find a replacement gear, but the speedometer gears are matched to tire size and final drive gear ratio, so make sure you get the proper replacement gear. If I remember correctly, the driven gear will have an identifying number stamped on the end, that is if the gear hasn't been destroyed. Or is at the bottom of the transmission.
The drive gear is located on the transmission output shaft, and is only accessable after disassembling the transmission. Of the two speedometer gears, the driven gear is usually the one that fails.
Harvester
