MerCruiser Sierra 18-2180 45-42634 Driveshaft Alpha One Gen 1 Lower Unit 1983-90

• Sierra Marine 18-2180 MerCruiser Lower Unit Drive Shaft Equivalent to 45-42634 used in all MerCruiser MR & Alpha One - Gen I lower units 1983-1990 <<<---Please make sure that the one you are replacing does not have a pre-load pin****
  • If you are looking for one with a preload pin (1970-1982), please contact us and we should be able to help.
• Very little / Normal wear on the splines.
• We left the bearing on here, it should be good, but you will want to check it before installation and replace if necessary. This listing is primarily focused toward the drive-shaft itself. For your own piece of mind we would replace the bearing, but this is ultimately up to your discretion. 
• In a nutshell 
  • Used on all subsequent MR & Alpha One Gen I drives 1983-1990.
  • In short, it replaces all driveshafts that did not have a preload pin.
  • They used the same Alpha One lower gearcase with all of the engines, as the upper gear case was responsible for the gear ratio. 
• They used the same lower gearcase with all of the engines 1983-1990 so your 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...
• Same as Sierra 18-2180
• Other Parts Included as pictured
  • Retainer 11-42632 / 82519 1
  • Race from bearing 31-36387A1 (Bearing is still on the shaft)
• Purchase with confidence!

1983 1984 1985 1986 1987 1988 1989 1990