Horrible clunking noise when driving

The car makes loud rhythmic clunking when driven at all speeds in all gears. The noise comes and goes and varies as to severity. the noise is related to speed. It goes away when the clutch pedal is depressed. The sound is unrelated to turning, accelerating in turns is no worse than going in a straight line leading me to doubt cv joint problems. Today as I was on the highway another driver shouted to me that it was a bad axle and noted that the sound dissipated under acceleration which it was doing at the time, however the sound has a phantom nature coming and going under different conditions. I brought it in to a mechanic who diagnosed a bad throw out bearing at the very least and suggested it needs a new clutch and possibly a new transmission. Wouldn’t a problem like that cause the noise to be heard at a stop rather than only occurring when the vehicle is in motion? If it needs a clutch I will most likely scrap the car but if it is a cv joint or half shaft it may be fixable. Any ideas?

Find another mechanic, that one should be able to diagnose it closer that ‘this, that, or maybe the other thing’. If someone in another car hears it loud enough to yell at you about it, a mechanic should be able to figure out what it is. Use the mechanic finder if need be: