Need help with serial and model# for force 150

[thecrownwrench]

I just bought a boat with a force 150 hp. The serial and model numbers are not visable.They are rubbed off the sticker.Older mercs had a number stamped into the power head is there a chance force had a similar system?The boat and trailer are 1989 most likely the engine is to but I would like to make sure.
Thanks