rear end issues

[97 Powerstroke]

i have a 97 powerstroke it had 4:10 gears in it with the ford f250 front end so i swaped the front end and rear end which came from a 86 f350 and now it wont shift rite the overdrive light blinks i cant figure it out why its doing it anyone have suggested thenk you

 

[DEERE3594]

Both had the same gearing?

 

[Shlep]

Your diff have a speed sensor in it? I know your old one did but I don't think your new one had the hole for it.

 

[THEFERMANATOR]

Your diff have a speed sensor in it? I know your old one did but I don't think your new one had the hole for it.

This would be my bet as well. Does your current rear diff have the speed sensor in it? Did you re-calibrate the signal to the PCM for it to shift properly with the new axles if you changed gear ratios or tire size? That is a fully electronic transmission and shifts using engine load vs RPM's and vehicle speed. If you change even one of those factors without re-calibrating it it won't shift properly. Let alone if you change 2 factors by swapping gear ratios and tire size. And without the vehicle speed sensor reading it cannot shift properly. And why did you change out to the older axle anyways? Aren't they both FORD 10 1/4 STERLINGS?