I just bought a 97 e-350 SD van which was orig 5.4 gas and now has a 2002 7.3 diesel transplant. ( I didn't know this at the time and know no History about it) It seems like they changed the engine, trans, computer, wiring and gage cluster.



My speedo is 15 mph slow. Showing 60 at 75 mph actual. Trans seems to shift ok, goes into od and lock up and cruise works.

I took it to the ford dealer to adjust in the computer and they said they adjusted it within 4mph and when I drove it there was no difference, Lol

I have been searching and and still not quite clear.

Is the speedo from the sensor in the rear or the sensor on the tail of the trans (VSS) Does the vss have changable gears?

So my question is can it be done thru the abs module and can you use the auto enginuity program? Or do you have to go into the PCM also. My tire is a 265/75/16 and stock is 245/75/16 so how can I be so far off. I have 3.55 rear and maby the donor had 4.10 is what I'm thinking ?? Is this affecting all my shift points? If you just let off the petal at 50mph the trany disengages untill it hits 35mph on the speedo then engages again like engine braking but I'm really going about 45mph....

Thanks for any help.
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