E350 2wd to f350 4wdh

Hello, looking for opinions. I have a customer that has a 2001 Ford E350 2wd that was converted to 4WD. The shifting and speedo are way out, reads 50 MPH at 10-15 MPH. i have tried to change the VSS to the proper tone wheel teeth but no matter what number i entered the shifting and speedo never changed.

I looked at a F350 file and it has more calibration parameters in the speedo cal tables than the e350.


Can I Flash the ecm to a F350 4WD? will it brick it? or just not work.


thanks