Your 1993 4x4 truck should have a 4L60E unit. Have you checked?
I'd find a different tranny guy. If the radiator trans cooler is clogging up , it will be from trash from the tranny.
You need to diagnose the problem. A weak 3-4 clutch pack will cause problems in OD and 3rd gear may work OK.
You could have a weak shift solenoid.
Low pressure can cause the problem from a weak spring , worn boost valve , a weak force motor that controls pressure.
The band can be nearly burned up and it will hold power in 2nd gear and NOT hold power in OD since the 2-4 servo is a multi stage unit
I'd find a different tranny guy. If the radiator trans cooler is clogging up , it will be from trash from the tranny.
You need to diagnose the problem. A weak 3-4 clutch pack will cause problems in OD and 3rd gear may work OK.
You could have a weak shift solenoid.
Low pressure can cause the problem from a weak spring , worn boost valve , a weak force motor that controls pressure.
The band can be nearly burned up and it will hold power in 2nd gear and NOT hold power in OD since the 2-4 servo is a multi stage unit