I have a 242 project I'm going to be putting a 525sc into , does anyone know if the mercruiser 9 prong plug is compatible with 525sc plug ? I'm sure I'm not the first to do this are there any other things that may hold up completion ? Going to start this as soon as it warms up , I will post pics and progress as it comes together should be a fun ride ! Any input will be appreciated thanks .

pretty sure 9 will plug into 10, but obviously 10 wont plug into 9, meaning boat harness 10, engine 9

Got it motor has 10 boat has 9 what's my best course of action here ?

Assume its an LS? Please let us know the progress very interested. Thanks.

Yes LS , just need to figure out what to do about the mercruiser plug ?

New boat side harness from mercury, under $200

Red you don't have a part number do ya ?

http://bpi.ebasicpower.com/pc/MAR6199-02-06/ALL6I

Looks like 80 bucks

What should I do change the plug on the boat or can I just change the one on the motor ?

[ATTACH=CONFIG]519895[/ATTACH]
This is the connection I have in the boat