Thanks Roscoe. That's a lot less than I imagined as I figured that the older technology would weigh more than the modern outboards. I'm looking at repowering with the 1998 115 Mercury which weighs 350lbs so the difference is about 3/4 of a tank of gas.
Alan, try 365 lbs for 20" shaft and 370 lbs for 25" shaft. The OMC brochure for that model year had incorrect weights, which must have been Roscoe's source.