1990 Ford F-150 -- that sound in the transmission

Hi...... When I start my 1990 Ford F-150, and put my truck in any gear, there's a 'clakity-clakity' sound coming out of (I think) the transmission. In neutral, that sound isn't there. And when I drive the truck, either the sound isn't there or it's VERY slight. (I'm not driving the truck now. It's 'retired'... waiting to be sold.) But I would like to know how serious a problem this is. One mechanic told me that there's a particular little piece of metal that might have broken off in there... and that it doesn't cause much damage... but DOES cause metal shavings to be distributed throughout the transmission. Not so good, huh? Please tell me what's going on. I know nothing!

Thanks...... artman49 Artman, First of all if you are at a standstill and the noise is present there is nothing moving in the transmission, so it's not in the transmission. It could be in the torque convertor especially if you have an E4OD trans. I would check to make sure all of the torque convertor nuts are tight, if they are good you probably need a T.C. They have numerous problems with these.Car Repair Talk's forum.