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Discussion Starter #1
My uncle has asked me to help in find out information to swap[ a manual 5 speed in his 1986 F250, 6.9 diesel, 4x4 that has a manual 4 speed in it. His truck is in showroom condition and he wants the swap to look clean and factory installed.

What model transmission she we look to get for the 5 speed swap?

What model and year trucks should we look to find that 5 speed trans to swap?

What all parts will need to be swapped?
 

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any 5 speed from a 88 to 97 ford diesel truck. it is a ZF-5 speed trans. the 88 to 95 or 06 used the ZF-42, the 96-97 used the ZF-47. slightly different gear ration , but either will work.
 

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Discussion Starter #5
Alright sounds good. now he did tell me he would like to buy one that has been already remanufactured to get warranty and not get another trans that would need rebuilt. what parts would we need to find (shifter, shifter boot, floor plate) or is all this the same for the swap?
 

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you will probably have to get new driveshafts built, and a crossmember unless you can find an 87 to 91 truck in a junk yard to steal them from, the transfer case adapter should be the same between the the 4 speed and 5 speed. the benefit of using a donor truck is getting everything you need all at one place.
 

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we almost did one of these in my old 6.9 years ago. IIRC it was going to need a different flywheel. We abandoned the idea because the top end difference was very minimal.
 

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If the 5 speed will bolt up to your engine / flywheel as stated above then it man be possible to just move your cross member if needed

The 4 speed trans is likely shorter then the 5 speed trans, so the X member and transmission mount may need to move on the frame rails a bit (drill new holes)
If your t case is manual shift the linkage between 4 and 5 speed may be different also
As stated above the flywheel and starter may also need to be changed

So getting all the pieces you need from a single donor truck would be the best approach, often you can get trans/shifter, flywheel, starter, t case, shift linkage, x member, mount, and driveshafts all in one place
When looking at donor you can also decide what has changed from your 4 speed setup to the 5 speed, a tape measure can really help here
 

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I did this exact swap in an 84 6.9 about 3 yrs ago. The T18 4 speed is almost exactly the same length as the ZF5. So it will bolt right in. Even the slave cylinder is the same. The driveshafts and transfercase shifter will all swap over absolutely zero issue there. There are, however, 3 minor issues.

1) The crossmember for the 4 speed is no where near being correct for the zf 5. You can either A) get a 5 speed crossmember and drill new holes in the frame because the frame will not have the correct holes for the 5 speed (as the 5 speed was not even an option in 86) or B) You can make your own cross member. This is what I did. I made it out of a piece of scrap channel iron and some angle iron. This took me maybe an hour.

2) The input shaft on the 4 speed is 1", the ZF5 is 1.25". So you will need to get a flywheel/clutch for a 7.3. You can piece together a flywheel clutch combo for the 6.9 flywheel (using an aftermarket pressure plate and clutch disk for the zf5), but it is kinda a pain and I don't remember what part numbers you need. I would just get the 7.3 flywheel/clutch set up.

3) The cab floor where the shifter goes through is slightly off. the shifter will work, but the transmission shift tower sets at the very back of the cab floor hole. This isn't a problem. The problem is that the transmission tunnel is about 2" shorter than the zf5 tunnel. The problem with this is that when you go to jack the 5spd up in place, it will hit the bottom of the cab. That transmission hump/tunnel piece will unbolt, and swap out, but the problem with doing that is that your hole in your carpet and the hole in the floor will no longer match. So what I did was I put a floor jack with a short 4x4 block and I jacked on that transmission tunnel/hump right where the shift tower of the zf5 would hit. By doing this I "bent it up approximately 1-1.5". This gave me the clearance I needed and the carpet matches the hole and the floor and you can't tell at all from the inside. This allowed me to use the old T18 4 spd. shift boot. I did have to cut the hole of the boot slightly larger as the shifter for the zf5 is about twice the diameter of the shifter on the 4 speed. The best part of this option is if for some strange reason you ever wanted to go back to the 4 speed. It will bolt right back in it's stock location and everything will still be stock and look completely unmolested.

If you take your time and don't get carried away this is a very straight forward easy swap that can easily be done with 2 people on a Saturday (or even half a Saturday...........).

Best of luck
 
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