Chrysler outboards work by a model number to determine the year of the engine.

There are 2 locations where you may find the model number. Early Chrysler model engine had a stamp it on a metal plate and it was placed under the carburetors, inside the lower cowling, or pan.The model I.D. plates are usually found inside here but may be on the opposite side:

 

 

MODEL NUMBERS are VERY important in identifying your Chrysler Outboard.
Chrysler (and to a lesser extent, Force) tended to make as many as 15 variations of a given motor in any particular year, many with not-quite-the-same parts from one to another.

CHRYSLER 3.5-150 HP OUTBOARDS MODEL YEAR GUIDE - Please click HERE. 

Force outboards used model numbers on vinyl tags, many of which washed out. If the number washed out, you may find a small sticker either on the cylinder head cover or the starter bracket.  

 PLEASE CLICK HERE FOR ALL FORCE YEAR MODEL GUIDES