99 F250 bad 5.4, 5spd, 4x4. can I replace with late 80's 302/351?

Asked by Apr 14, 2017 at 07:57 PM

Question type: Maintenance & Repair

11 Answers


No you can't do a swap, engines are not compatible. But like TrannyMan said, if you have a big pocket book, then you can do anything you want.

I just want to clarify. The question is about engine swapping a 99 5.4 with a late 80s 302 or 351.


No, the engines are not compatible with each other. The 1999 engine is controlled by a OBDII computer and has a totally different set-up than the 1980's models, which are controlled by a OBD1 computer. Totally different.

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OK. Is that the only issue?, as I have both complete running trucks. 1 is 89 f150 lariat, 302at 4x4, also have a 87 f250 custom, 351 5spd 4x4. 99 f250 is also 4x4 idk if that matters.


Well then you would have all the parts to make it run. It is possible to do then, you'll need all the wiring harnesses to switch out along with switching out the computers. You will need the transmissions also with the transmission control module. Just a lot of work.

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OK thanx. So I could put an 80s eng in but would need 1. computer with harness, correct? 2. Trans module and harness or need to swap trans, correct? As far as mounting points..my engines will NOT (?) bolt up to what spec, mtr mounts, bell housing? Was hoping that the 99, being a std, would be able use a mtr that i already have. I really don't want to replace with 5.4, I think theyre junk, in generally speaking I have the same opinion about auto trans and computers. I don't however have anything against carburetors. If the answer still comes to cost, what engines will bolt in without all Fords bs?

Aww my apologies to your feelings n my thanks to your intellect. I was hoping (but not expecting) that my older engines would match the newer std bell housing and mbe using a carburetor etc. would solve the electronics issues. OK ty n all for help. What options remain, i hope another 5.4 isn't the only answer.

Ty for the hint about the tritons. OK. Is a 4.6 from a 98 f250 7 lug compatible to replace the 5.4? Besides swapn the computers, what other issues? The 99, 5.4 is a std, the 98 is auto. I want to stay std trans. Are there any issues with the bell housing, flywheel, crank, starter etc with putting a motor from an auto trans truck into a std trans truck?


Your truck will never be smog legal after such a swap which would render it unsalable.

Well thnx guys. Would've been putting an auto eng in a std truck bt fords idiot engineers are defintely making it awful hard to stay brand loyal! So TM just cant help noticing that it seems all the american vehicles have lousy trans. Why?

BTW Id stil like to know what years can replace the 5.4l in a 99 f250 5spd 4x4

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