Transmission Backlash?

I have a 2000 4.3l v6 2wd 5spd 85,000 miles. I've had it to two different repair shops and both tell me the noise I'm experiencing in the drive train is "backlash". When I let off the gas and reach that equalization point where the truck bucks I get the loud clunking sound. If the truck bucks at lower speeds (up to about 20 mph) I hear a squeaking sound. I took the backlash answer as an "I can't be bothered right now" response so I changed the u-joints. Still no difference. I don't mind the noise so much...I just don't want to be stranded some where along my 70 mile commute. Thanks.

Drive train noise in these trucks are common. Especially what you describe.