The truck in question is my 95 f150. It has the 4.9 with m5r2 trans. I also have another f150, a 1989 with 351w and c6. I was wondering if I would be able to swap the 89 engine into the 95 without too many issues. I would have the radiator, engine stands/mounts, computer, wiring harness, etc from the donor truck. Would I be able to use just the under-hood harness? I would probably put fresh gaskets, water pump, possibly timing chain, etc. on the 351w before it went in, but I would not be building it any past stock. I realize that the m5r2 is probably not the best choice of transmissions. Would I have to get drive shafts shortened/lengthened if I kept the m5r2 and x-case that is already in the 95? I realize that I would need a flywheel for the 351w.

I figure that because both engines are speed density that I won't run into too many issues, but my main concern is about the wiring harness/es. I have done a bit of research, but I am not sure about going with an 89 engine in a 95 pickup. Any and all suggestions/comments/concerns are welcome.

 

comparing the pinouts for the computer and where the "underhood" harness plugs in would be the easiest way to see if you will have to rewire under the dash. but I couldn't tell you solely from experience.

I agree that the m5r2 isn't the best, but if its what you got, i won't say anything against using it. shouldn't be no difference as far as driveshafts go, i just swapped out a 302 for a 300 in my bronco and none of that changed, and by having the doner truck you will have all the little peices.

are you sure about your 95? my dad had a 94, and it was mass-air...

 

100% positive, speed density. Dual tubes coming off of the air cleaner box, and no sensor in the tubes anywhere.

 

The under hood harnesses will not simply interchange... not even close, the '95 has a large block connector while the '89 has a bunch of little connectors. The upside is that very little of the original 4.9 harness has to change to adapt it to a V8, the biggest thing is adding an extra injector plug on each bank, otherwise there may be some wire lengthing and re-routing but that's it, so you really don't need to change the harness.

 

If it's not going to be "plug-n-play" I'm not gonna screw with it. I don't have the time to mess with something like that, I'm a full time college student, I work part time at the local airport, and I work full time on our farm. I couldn't afford to have my truck down for a month while I tried to figure that wiring mess out.