I have a 1997 F150 Supercab 4WD 4.6L V8 with Electronic 4 speed auto transmission and electronic 4WD xfer selector. The truck has 253k miles (I bought it new, mostly hwy, VA-DC rush hour on I-95). The truck has always run great, however 2 days ago the tranny started making a horrendous noise when in any gear (any fwd gear or reverse) with the vehicle stopped (loud mechanical clanking/rattling type of noise) that went away as soon as I got moving > ~15 mph. All gears shift normally and there is no abnormal noise or performance once I'm moving. Any ideas or help on what the problem could be would be appreciated. My first thought is the torque converter?
Thanks a lot,
Gary