If you have a 1994 0r 1995 you have a 47RH transmission.
If you have a 1996-2002 you have a 47RE.
I would first check your fuel pressure. If you have low fuel pressure you would have lower power. That may be the difference instead of the transmission.
If your tc is slipping it probably needs to be replaced. It has a clutch inside just like a brake lining. If it is worn out it is worn out.
What year is your truck, what modifications have you done to it?
Look here for transmission troubleshooting links. The 47RE has a lot in common with the 47RH. The big difference is more electronics in the valve body.
94-98 Drivetrain (except engine) - Dodge Cummins Diesel Forum