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Upper & Lower 1.81 Ratio

Alpha One Generation 1 - Complete SEI-106 - Upper & Lower 1.81 Ratio

$USD 1,759.00$USD 1,959.00

Mercruiser alpha One gen I Complete Replacement Outdrive Unit, Replaces 1.81 ratio for Oldstyle and new style counter and standard rotation


SKU: SEI-181 Category:

Product Description

Sterndrive Replacement has some upper & lower SEI-106 (SEI-181 Outdrive, Replaces 1.81 Ratio alpha one gen 1) units at the best overall prices in the U.S. market. Even though our prices are the cheapest you will find, know that our products are not rebuilt! They are aftermarket quality parts.

With any Upper and Lower purchase, Sterndrive Replacement lets you benefit from our 3 year warranty, providing you with 3 years of full coverage. Only at Sterndrive Replacement.

This is a replacement for Mercruiser sterndrives alpha one generation 1.

This Mercruiser sterndrives alpha one generation 1 unit is a replacement for 165-205 HP and up from 1976-1990.

  •  Outdrive from 1976-1982 470 HP.
  •  Sterndrive from 1980-1982 485 HP.
  •  Mercruiser Sterndrive 1977 250 HP.
  •  R/MR/Alpha One 1983-1990.
  • 1983-1990 include 3.7L inline 4, 4.3L V6.
  • 1983-1990 include 224, 262 CI.
  • 165, 170, 175, 180, 185, 190 and 205 HP Mercruiser V6 3.7L Mercruiser inline.
  • 4-cylinder engine.
  • Replaces most Mercruiser sterndrives 120-260 HP from 1967-1990.
  • Your Mercruiser sterndrive must have trim and tilt to be able to use our replacement drive.
  • To determine if you have a counter rotation unit on your twin engine boat, it is easiest to look at the propellers. If your propellers are identical orientation, they are both standard rotation. If the propeller blades are opposite, then the port side should be counter rotation.
  • If your unit has a short yoke on the upper driveshaft, we refer to this has a “Old Style”. This applies to all inline 4-cylinders and inline 6-cylinders engines, up to and including 1982.
  • Unit must have trim and tilt for 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 cover utilizes the new style flat top.
  • Unit has a round cavitation plate on lower unit; replacement unit utilizes the newer style shift.
  • Unit may have an o-ring and/or a preloaded pin on lower unit driveshaft. The replacement will be square.
  • Gear ratio must be confirmed. To be safe, it is best to remove the top cover and count the teeth on the upper gears.

with a 9-9/16 new style input yoke.
Install Kit or Anode Kit not included.

NO warranty over 300 HP.


Additional information

Weight 110.0000 lbs
Rotation & Style

Standard Rotation 1.81[=1295], Counter Ratation 1.81[=1495], Standard Rotation oldstyle 1.81[=1295], Counter Ratation oldstyle 1.81[=1495]