Change-out a 1994 merc 75elpto for a 2003 50 elpto

[billybob141]

I have a 2003 kenner 18vx with a 2003 merc 50 elpto sn# OT742537 (underpowered). I have a 1994 18' bass tracker pro-18 with a primo 75hp tracker elpto sn# 0G086732.
Can I simply unplug wire harnesses and change motors from one boat to next, or dooes entire wire harness have to be swapped as well?
Will the remote shifter/throttle cables be the same?
Any help will be greatly appreciated.
Thanks,
Billybob141

[boats.net]

The throttle cables should be the same. The wire harness are not the same. You will have to swap harness and control box.

[billybob141]

Change-out a 1994 merc 75elpto for a 2003 50 elpto

Thank You Boats.net...
By any chance can you please exlain what you mean by control box?
Thank you.

[boats.net]

The control box is where you throttle the motor.

[billybob141]

Change-out a 1994 merc 75elpto for a 2003 50 elpto

The control boxes are vastly different.

New Boat= On the boat I am transferring the 75HP to;
the control box is a top-mount style.
This control box contains the neutral switch, and Trim/Tilt only.
The keyswitch and kill switch mount seperately on the Center console.

Old Boat = the vessel I'm taking the 75HP from;
the control box is a side mount style.
This side mount contains the neutral switch, kill switch, and Trim/Tilt.

Can you please explain why you think changing the cotrol box is necessary?
Thank You much..

[boats.net]

In 1996 BRP changed the wiring harnesses, The wiring harness will not work together.

[billybob141]

Swap now Completed.

Gents,
I have completed the swap of the 1994 75HP Merc in place of the underpowered 2003 50hp merc on a Kenner 18vx.
The swap was very easy and a plug-n-play.
Same bolt pattern on transom, same wire harness connection inside cowling, same throttle and shifting linkage connections, same fuel connection, and steering cable connections.
I bought a Flywheel lift hoist tool (ring screws into the top of Flywheel) to hoist motors.
End result.. Top speed with 50hp was ~ 22 mph, now~35mph; Fuel consumption was ~5Gph to travel 20-22 miles at WOT = ~4.4 MPG, now ~ 30mph at 4200 RPM ~ 5gph ~6MPG cruising... ~35mph consumes ~7.5 GPH for ~4.6MPG WOT.. Not Bad...
Thank You All for your advice.
Booger