1996 Manual Transmission Fluid and Change on 1999 Ford F-350 Super Duty

I have checked with the Ford MC and local parts and service shops and no one can tell me
what kind of Trans fluid I need for my 1996 Ford F350 Manual Transmission and how to change it? Please Advise!

Asked by for the 1999 Ford F-350 Super Duty
You should use mercon synthetic automatic transmission fluid