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Hi, My T-18 in my 89 4.9l 2 WD F-150 went out out and I would like to replace it with the 5 speed M5OD. Has anyone ever done this? I am having a bit of a problem finding one. I hear that there might be some driveshaft modifications needed (that what one of the rebuilders told me). Anyone have any info on this exchange?
Yes, at the *very* least, the transmission output shaft is going to be different than the T18, so you're going to have to change that yoke. I also do not know if the Clutch pedal setup (I assume it's hydraulic, it's been a long time since I worked on an OBS with a 4-speed) is going to be compatible with the input shaft mounted slave cylinder on the M5OD. It's not impossible that you'd need to get the right transmission tunnel cover, to match up with the M5OD shifter location as well.
I have that trans behind the 6- it's a good match BUT it's a 'car' transmission:
as in, 1st gear is great at stoplights in traffic, but it's awfully fast if you're using
the truck in the woods or fields. Mine's 4wd, so I use low range a LOT
when I'm hauling, pulling, pushing or otherwise breaking things.
It has an integral bellhousing, so that's covered- if you have a hydraulic clutch
for the t18, that should work as well- but check to make sure the master
cylinder is the same diameter between the 2. Plumbing will be different.
The driveshaft will be different, as well.
If you have a mechanical speedometer coming off the t18,
finding an M5 with mechanical speedo might be difficult. 88's electronic, tho, innit?
You can probably find a bricknose truck with 4.9L and M5OD in a junkyard and use the driveshaft from it.
While you have it out you might want to go ahead and change the U-Joints.