Alpha 1 & Gen. 2 Outdrive Parts *Drawings *Videos

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Mercruiser Alpha One gearcase (new lower unit)

Lower unit gear housing assembly replacement from GLM Marine aftermarket parts

  • New complete lower unit gear housing assembly replacement
  • Forward bearing size: O.D 3.500 (#21590)
  • Heavy duty construction replaces original Mercruiser and Alpha 1 (One) lower units
  • OEM 1623-8951A43
  • GLM # 18100
  • Gear ratio: 13:21
  • See our Alpha 1 lower unit page for all lower gear case parts and components with photos
  • Tech support exploded view drawings search by part number or description here

lower unit complete

lower unit complete

gearcase assembly

gearcase assembly

prop shaft lower

prop shaft lower

P/N 18100 - MerCruiser Alpha 1 (One) lower unit gearcase assembly

$1399.95 (No core required)