Mercury Mariner Outboard 40 45 50 60 70 HP 20" Lower Unit Gearcase 1643-9539A5
This is a good working lower unit. The oil was clean when drained and passed the pressure test (15 psi for 20 minutes).
The driveshaft has 11 splines and is about 22 1/4" (from the top of the gear housing to the end of the driveshaft pin).
The prop shaft has 13 splines.
The water pump was not inspected but we suggest replacing the impeller before use.
You will need to re-fill with new gear oil prior to use.