i serviced my tranny at 47,500 mile because I bought it used in 2003, now around 120,000 tranny has starterd to have a hard down shift from OD back to drive on highway, like when passing . literally shakes truck a little on downshift.
tranny shifts fine in all gears and , did slip in 2nd gear pulling my small camper 1 time, fluid not burnt,
im leaning toward torque converter issue,
so I dropped pan again at 130,000 miles changed filter and added a can of lucas transmission fix to it, seems to made it shift a lot easier and too some of the mump out but still there.
what do I need to do?

 

I stopped running superchip tuner at 100,000k

 

The shift into overdrive releases the forward clutch while applying the overdrive band. Shifting out of overdrive does the opposite and releases the OD band while applying the forward clutch. Forward clutch pressure is also on the release side of the OD servo.

So I'm wondering if something is going on where the OD servo isn't releasing quickly enough.

 

. Is it a piece a can buy and put on the outside of trams or is it all inside?

 

Well, the OD servo piston is inside the pan under the valve body. I would consider replacing both. Maybe even the EPC solenoid. If those 3 things don't correct it then it's truly either not transmission related or is inside the case.

D