I just traded my 1993 Ford F150 4.9 liter 4x4 with 80,000 miles short bed for a 1994 Ford F150 4.9 liter extended cab short bed 4x2 with 76,000 miles. Right off I noticed a shudder or vibration in the transmission around 40 to 60 miles per hours. Used dealer told me that they would do filter and fluid change and solve the problem. I told them I wanted a new torque converter since my 1993 went out and was doing the same thing. Just got it out of shop and it runs great now. But I wonder if they just replaced fluid and filter or acutally did the whole thing. Any good way to tell guys? Also I believe this is getting better mileage now compared to my old 4x4. Also I have had half the people tell me to turn the over drive off when heavy towing and the other half say leave it on unless you go down hills and want extra braking. The manuals I have say leave it on and use it for braking. Anyone no. I don't yet have a cooler on the tranny on this one yet. Thanks.

 

To get at the TC, the bellhousing would have to be unbolted from engine, and trans pulled back. Could look for evidence of recent bolt turning on: Bell housing to Engine, Trans rear support at crossmember, shift linkage at trans, and at least one end of the driveshaft would have to been unbolted.
As to the O/D or not O/D, I thought the facts behind the arguement was whether or not the TC lock-up clutch was locked, or not, due to the particular load and conditions.
Example: Heavy load, O/D off (3rd gear), pulling OK, TC lock-up clutch engaged, so no slippage in trans equals less trans heat.
Or: Heavy load, O/D on, if actually in O/D (4th), if TC clutch unlocks to help pull (much more likely due to O/D ratio!), and stays unlocked due to load in this gear, then slippage goes on and on, creates more heat, etc.
Separately, although a lower gear means higher engine RPM, that revving engine has a lighter load than when coupled through the O/D gear.