Sterndrive Engineering Replacement Lower Unit Mercruiser R, MR, and Alpha One

Sterndrive Engineering Replacement Lower Unit Mercruiser R, MR, and Alpha One

90-106-02

• Replaces R, MR, Alpha One lowers from 1972-1990
• 13 Spline Driveshaft
• Tooth count is 13-21
• Up to 300 HP

90-108-02

• To replace Counter Rotation units only

Item is subject to a 20% restocking fee (Boat Covers, Bimini Tops, Outdrives, Drop Ship Items and Special Order Parts)!

**Year, Serial Number, and Horsepower are required to order. Please contact us with this information after you place your order otherwise processing will be delayed.

Sterndrive Engineering Model Chart

Refer to Sterndrive Engineering's model chart below to find your proper Mercruiser Sterndrive Replacement. These are typical applications; it is best to confirm your ratio by couting the teeth in the upper. Although great care was taken in the creation of this guide, its accuracy cannot be guaranteed.

Notes:

1. Unit has an 8 spline driveshaft on the lower unit. If your unit is original, you need to purchase a complete.
2. Unit has a short yoke on the upper driveshaft. We refer to this as the “Old Style”
• ***Applies to all inline 4 and inline six cylinder engines up until and including 1982***
3. Unit must have trim and tilt for our Replacement to work. If it has two trim hoses going to each cylinder, it has trim and tilt.
4. Unit has an eyelet on top cover. Replacement unit will not.
5. Unit has a round cavitation plate on lower unit. Replacement unit will not.
6. Unit may have an o-ring and/or a preload pin on lower unit driveshaft. The replacement will not.
7. Gear Ratio must be confirmed. Chart below is typical applications, however there is no guarantee it is correct. To be safe it is best to remove the top cover and count the teeth on the upper gears.

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