SE218 (Replaces Most Mercury 3.0L Counter Rotation)

SE218 (Replaces Most Mercury 3.0L Counter Rotation)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

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).