Drop the pan, replace the filter and gasket, replace the pan and add Transmission Fluid.
It is inside the oil pan, is this is automatic. If not, there is no filter.
The manual shift transmission does not have a filter.
Check your Automatic Transmission fluid level
according to a local dealer that model has no modulator valve on its automatic transmission sorry !
the filter is inside the transmission. the transmission has to be disassembled to get to it.
To Change the filter in a 1988 dodge ram van you have to drop the transmission oil pan, peel the old gasket clean the surface and then replace the old gasket the filter is inside the transmission time to replace is usually 30 to 45 minutes most oil change shops offer that service or you can do it yourself cheap.
should be a C-6
normal atf
700R4
700r4 if its an automatic
it has an oil filter, fuel filter, air filter, but no trans filter.
Diagnose it with what? Cancer?