Re: 1988 20hp Evinrude - lower
are you sure it"s the LU and not the motor? Drop the LU and see if the power head will turn over ( spark plugs out with a socket on the flywheel nut, or try with the recoil.
If indeed it's the LU, they show up on eBay, but there is no way to know if you are getting one in any better shape than yours.