MerCruiser 43-878087A4 Lower Unit Gearcase Gear Set Alpha One MR 1983-1990

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Item Details

MerCruiser Sterndrive Alpha One Lower Unit Complete Gearset 43-878087A4 (Pinion, Forward, Reverse)

Used in MerCruiser MR & Gen I lower units 1983-1990
- These are the correct gears if your lower gearcase DOES NOT HAVE A PRELOAD PIN on top of the driveshaft
  - ****If your gearcase HAS A PRELOAD PIN, then these are not the correct gears*****
Pinion Gear (17 Teeth): 43-42932 (Same as 43-89060)
Forward Gear (28 Teeth): 43-42933-2 ( Sometimes Stamped 17064-6022)
Reverse Gear (28 Teeth): 43-42934 / 43-824109A1
Don't worry too much about the numbers here as the numbers changed, but the gears didn't 1983-1990

Used but in great shape!
- I highly recommend that the bearings that are included (still attached to the gears) should be replaced. However it is up to your discretion as to whether or not bearings should be replaced.
Application
- For MR & Alpha One Gen I Units which have the pre-load pin in the top of the drive shaft. (If your unsure what this means, just ask)
  - This gear set will not work in a MC-1/Pre-alpha & R gearcase (I apologize for the redundancy of this statement)
- They used the same lower gearcase with all of the engines 1983-1990 so you're particular engine is not a factor here so this basically covers most (120hp 140hp 4cyl 165hp 6cyl 170hp 305 350 470 260hp 2.5L 3.0L 4.1L 3.7L 3.8L 4.3L V6 205hp 185hp 5.0L 5.7L V8 etc...
Freshwater Used Parts
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Relevant Part Number List

Please inspect pictures closely to to ensure product satisfaction.

1983 1984 1985 1986 1987 1988 1989 1990