FLD 120 speedo/odometer

Hello.

I have a 1995 freightliner classic with a 3406E 550 CAT in it. My speedo is currently all over the place and my odometer has quit working. I checked the sensor for my RPM and that is fine. I have replaced the speed sensor in the back of my transmission and that is fine. I have pulled the wires out from my speed sensor all the way to the ECM to check from breaks or abrasions that is fine. Then i figured it was the cluster in general so i replaced the unit and still it is acting up..... I am at a complete loss i dont know what else to check and or replace. I have read on some forums that it might be my ECM.

Any suggestions or information would be much appreciated.

Thanks For your time.

Mitch