Will an '87 2.5 fit in an '84? What needs to be changed?

Yes

You will need to re-work the harness and use the 87 ECM, DIS but modified to work with the 84 body harness.

I replaced an '86 2.5L with an '87 2.5L; the fuel lines to the TBI are on opposite sides; swap the water pump outlet casing from the '84 to the '87 to keep the heater hose connection; you'll need the '87 accelerator cable right from the gas pedal; the '86 harness connections plugged right into the '87 ECM except on the side instead of the bottom so get the '87 mounting bracket (the '84 may be different). I'll add more if I think of more...

Added: Vacuum lines will need adapting including the line to the power brake (Easy, but on the list). I think that's the extent of issues other than the wiring differences that Phonedawgz is your go to guy for... I have an '84 as well & nothing else came to mind when I was looking at it and the '87 2.5L in the '86.

[This message has been edited by David Hambleton (edited 06-03-2014).]

84 body harness has C500 in a different location and wires different on both C500 and C203. So you will have to modify the engine harness to fit the 84 body harness, or modify the 84 body harness to match the 87 engine harness.

Since you will have both engine harnesses out of the car, my thoughts are that modding the engine harness will be easier.

Thanks for the replies.

I just did this exact swap. (I will be doing a write up soon) You would be suprised at all that is neede to change. Just wow.
Doing the swap I found out at how many things on the 84 are different. and had to be changed
(This is no where near a complete list) (to do the swap)
Throttle cable
Harness
Dash/gauges wireing
oil pressure switch
heater lines
A/C lines
shifter
shift cables
ECM
C500 location
Backup light switch location and switch itself
Air box, (have to cut the frame to fit a later year)

So it WILL fit and work, as proof there is one driving around Vegas now, but it is not plug and play.
(A write up will be coming)

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