That should be a 2:1 gear ratio lower unit. You can divide the number of teeth on the pinion into the number of teeth on the forward or reverse gear to confirm. Unless the skeg broke the lower portion of the gear housing, it should be repairable at a welding shop that is familiar with lower units. Also, if you do decide to replace the housing only, the gears will have to be installed and shimmed to specification. Otherwise the gears will be short lived. Good luck with it.