Mercruiser Alpha One Replacement Upper Unit 1.81 - MW

Name: Mercruiser Alpha One Replacement Upper Unit 1.81 - MW
Brand: Sterndrive Engineering (MW)
SKU: S-E-90-106-01B
Availability: InStock

SKU S-E-90-106-01B MPN 90-106-01B MFR Sterndrive Engineering (MW)

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Back to: Mercruiser Replacement Drives

SternDrive Replacement Upper Unit for Mercruiser R, MR, Alpha One. 1.81 Ratio

1.81 Ratio also replaces 1.84 ratio
For Alpha One Gen I Sterndrives (1972-1990)
Comes with a 9-9/16" [new style] input yoke.
3 Year Manufacturer's Warranty
OE#9412A22

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.

Model	Year Range	Serial Range	Notes (See Below)	Standard Rotation	Counter Rotation
120,140	1967-1969	2062141-2791956	1,2,3,4,5,6	1.94	1.94 CR
120,140	1970-1982	2791957-6225576	2,4,5,6	1.94	1.94 CR
160	1967-1969	2065190-2763441	1,2,3,4,5,6	1.62	1.62 CR
165	1970-1977	2763442 and up	2,4,5,6	1.62	1.62 CR
225-S	1974	3856268-4200499	4,5,6	1.47	1.47 CR
233	1975-1977	4200500	4,5,6	1.47	1.47 CR
250	1977	4791300-4898729	4,5,6	1.47	1.47 CR
260	1978-1982	4898730-6225576	4,5,6	1.47	1.47 CR
470	1976-1982	4208730-6225576	2,4,5,6	1.81	1.81 CR
485	1980-1982	4893835 and up	2,4,5,6	1.81	1.81 CR
888	1971-1977	3106717 and up	4,5,6	1.47	1.47 CR
898/228	1977-1982	4782330-622576	4,5,6	1.47	1.47 CR
R/MR/Alpha One	1983-1990	6225577-OD469585	6,7

Notes:

Unit has an 8 spline driveshaft on the lower unit. If your unit is original, you need to purchase a complete.
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***

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.
Unit has an eyelet on top cover. Replacement unit will not.
Unit has a round cavitation plate on lower unit. Replacement unit will not.
Unit may have an o-ring and/or a preload pin on lower unit driveshaft. The replacement will not.
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.

Engine Configuration	Horsepower	Gear Ratio	Tooth Count	Standard Rotation	Counter Rotation
Inline 4 Cyl. 2.5L/3.0L	120,140	1.98/1.94	20/24	1.94	1.94 CR
Inline 4 Cyl. 3.7L	170	1.84/1.81	17/19	1.81	1.81 CR
Inline 6 Cyl.	160/165	1.65/1.62	24/24	1.62	1.62 CR
V6 4.3L	185/190	1.84/1.81	17/19	1.81	1.81 CR
V8 305 2 Barrel Carb.	200	1.65/1.62	24/24	1.62	1.62 CR
V8 305/350	230/260	1.50/1.47	20/22	1.47	1.47 CR