Mercury Lower Unit Replaces Most Mercury 3.0L Counter Rotation Outboard

SE218 Replaces most Mercury 3.0L Lower Units (SN 1B504989 and below). Does not replace the Torque Master, Torque Master 2 or the Sport Master.

Available with a 25 or 30 inch (13 spline) 1 pc. driive shaft.

If you have an 8 Spline drive shaft, you will need to buy the stub shaft unit
and buy an upper driveshaft from an OE dealer.
25″ 45-823901A 1
30″ 45-824115A 1 (This item is no longer available from the OE. You will need to source a used one or fix your old drive.)

If you have a 13-spline two-piece shaft, just buy the appropriate
one piece shaft from the drop-down box above.
The SEI 218 gear cases are supplied with the correct water tube coupling for units with a serial number of OG438000 and higher. If your unit has a lower serial number, you will need to use your old water coupling or buy the correct part (SEI part number 96-116-12K).