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replace 2008 4.2 with a 2003 4.2, will it work?

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Old Mar 4, 2026 | 08:56 PM
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051
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replace 2008 4.2 with a 2003 4.2, will it work?

I have a good 4.2 in a wrecked 2003 f 150. Looking at a 2008 that has a bad 4.2. Thinking of buying the 08 and putting the 03 engine in it. Is this a direct fit? Both are automatic, 2wd, extended cab.
Any advice is appreciated.
Thanks!
051
 
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Old Mar 5, 2026 | 10:14 AM
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You will have to swap stuff. After 2000, it’s the same base blocks. Obviously, the intake is different, alternator I believe as well.



I think this video will outline differences over the years. I was looking at swapping an ‘08 4.2 into my ‘03 when that time had arrived, but I lucked out and found another lower mileage ‘03 engine instead.
 

Last edited by Johnny Paycheck; Mar 5, 2026 at 10:16 AM.
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Old Mar 6, 2026 | 08:28 AM
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Thank you!
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