http://www.mustangevolution.com/forum/v6-ford-mustang-engine-tech/9601-how-4-2l-swap.html

works for both 4.2L & 3.8L

gn86 said:

i blew the head gasket in my 96 convertible with auto transmission. I was wondering what is needed to make the swap to a 1999 or up engine. I know i will need a new ecu but was wondering what else needs to be changed. hope someone has done the swap and ould hepl me here. dont wanna go through the hassle of a v8 swap but the extra 50 hp and lwer miles of the 99 would be nice for the same price range

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thanks

I was planning on sticking with a stock 3.8 from a 99 up mustang. I guess my main questions are. what mods to wiring harness if any. Is the fuel syatem and plumbing the same and motormounts and driveshafts all line up? I am just wanting to replace the motor and ecu but if its not too many other mods i would like to swap to the newer motor.

you shouldn't have to change your ecu, just have it reflashed. everything else is the same.

the fuel system IS different, but not in a way that'll change anything but a CEL, but nothing the computer should recognize with the reflash. The block is unchanged.

The fuel rails etc are different, and if you have all of that stuff from a complete engine, then all you need to do is hook everything up, reflash the ECU and go.

You might pm v6sprout, but I'm pretty sure that's all you've got to do with a complete engine.

gn86 said:

I was planning on sticking with a stock 3.8 from a 99 up mustang. I guess my main questions are. what mods to wiring harness if any. Is the fuel syatem and plumbing the same and motormounts and driveshafts all line up? I am just wanting to replace the motor and ecu but if its not too many other mods i would like to swap to the newer motor.

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