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Hello guys, greetings from Honduras. I have a 97 4.6 4x4 Expedition with a dead engine. I use the car mostly for driving on the highway, with the load being a couple of guys that work with me, a couple of ladders and some electrician tools. I love the car due to it being very comfortable, since I am a 6' 4'' tall guy, and not precisely a slim one. I was considering rebuilding the engine, but as you know fuel economy is not good on this machine, and installing a 4BT sounds like a good idea, since that is a very common engine here and every block there's someone that tinkers with them. I was considering several configurations, but you are the experts and I would like feedback from some guys that really know what they are talking about, and not my local "half wrench"mechanics.

First option: Change the engine to the 4BT, and keep the transmission. How difficult is it from a mechanical point of view? Do I need to do body modifications? I want to keep my AC working as well. Does the transmission require change of converter? The electronics required to keep the transmission working worry me a bit too, since automotive electronics guys here are scarce. How complicated is it to hook one of those PCM, and get the speedmeter and tachometer working also?

Second option: Change the engine, and also change the transmission to a manual one, perhaps a M5R2. What do you think about this one? Which transmission would be a good fit both for the 4BT and the transfer case? Is it even possible on this car, or will it be too complicated/expensive? As I stated before, I'm not looking for high torque but for fuel economy during highway use.

I appreciate your help, and look forward to your comments. If the diesel swap seems to difficult or expensive, I was considering fitting a propane system, since this are very common in Honduras, due to gasoline costing twice the cost of vehicular gas. Anybody have experience with that as well?
 

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Welcome to the forum.

I think I would go with option 2. It's already been done:

 

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I'd agree with Bob. Using the existing auto transmission will be difficult. Shift points are wrong, will require a custom adapter to mount to the engine, a different torque converter, and an outboard control for the transmission. In other words, expensive. The M5R2-OD is reasonably strong and if not abused holds up well with the 4bt. On that one you'd want to make sure it is the SB Ford bellhousing and not the modular like your 4.6. Of course I don't know what engine adapters are common on the 4bt in your area.
 

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I know the post is a few months old now but finding an engine with the sbf adapter and using a m5r2 5 speed transmission is by far the cheapest way to go. Just off the top of my head, any of the 96-older f150 with 5.0 or 4.9 m5r2 or 97-newer 4.2l m5r2 transmissions should work. id have to dig a little deeper with spline counts but it should be right. The m5r2 transmission has a pretty fast 1st and reverse but 5th seems like it could be a little faster As far as the strength of this m5r2 transmission... I havent broke one yet but i have broke motor mounts trying to do a burnout... The video above is my expedition and i use it for towing and daily driving. . I have done a few cummins swaps and I am currently in the process of converting a v10 excursion 4x4 to a 6bt zf 5 speed.
 

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the only 1st-generation expedition converted to diesel that i've ever seen had also been retrofitted with a manual transmission, just don't remember which one

by the way, have you never considered any other engine, let's say, something out of a random japanese cabover truck?
 
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