How to replace Mercury manual trim with power

Would I need to get the entire Mercury power trim assembly if I wanted to convert from manual trim to power trim? Is it possible to just install the electrical stuff and motor? How do people usually go about this?

I was considering one of those CMC 130 units but I'm starting to think about not going that route because it would push my outboard further away from my tunnel hull.

To do it right, yes, you'd install the PT&T motor as an assembly to your motor. Also get the wiring and switches and relay(s).

I have never done a Mercury, but I have done a couple Yamaha's. One of the things I ran into was that PT&T motors had a different clamp bracket and swivel bracket-which adds significant cost to convert them. That is in addition to the already expensive PT&T assembly and the wiring harness/relay and switches.

The CMC is cheaper usually, but as you mentioned moves the motor back about 5.5". Never messed with tunnel hull, but on a normal semi-v or flat bottom, moving the motor back also allows one to move it UP an inch or so, which helps greatly in shallow water.

Saw a 1984 bass tracker for sale today and thought about buying it just for the power tilt/trim my boat lacks. How much money to add it?

Makes a big difference which year/model you are asking about.

I have a mid section for a 1998 40 force by mercury I can send some pic 859 265 1679
don't if it will fit

I converted to power trim this past winter on my 1994 60/45 jet. It was a full conversion kit I got off Ebay new, but it was not for my exact year so the relay bracket did not work. There's a few parts involved and you have to remove the pins from the manual setup and use new pins with the new set up. There's the switch and harness and the relay harness with bracket. If you search around you might find it new for cheap. I got my setup for $409 shipped, it retails around $900-1000.