I assume you've looked all over for the capacity plate; beside the helm, back by the motor pod, all the possible places? I'd guess max horsepower would be 115 and max load would be somewhere in the neighborhood of thirteen peeps. Interpretation of that number as it relates to weight capacity will be left to your ciphering skills. Please understand my response is based entirely on somewhat (read barely) educated guessing. Welcome to iboats.
there is an 1989 Grumman 24' on ebay for sale, I asked they guy what his plate said (mine is unreadable) he said 15 peeps but weight and HP were unreadable on his. I have an 89 and was hoping to find out what mine said.