need help

[Carolina kid]

I have a mercury lower unit. Not sure what year or weather it will bolt up to a 2.5 mid or not. The only numbers I could find on it was casted in front of the water pump. Theres two sets of numbers. First it has 1647 and under those numbers it has 9147c3 can someone please tell me what I have or point me in the right direction. thanks

[Raceman]

I can't help with it by numbers, but ALL Merc V6 2, 2.4, & 2.5 liter gearcases interchange UNLESS they're from different length engines.