So.. had a problem with my 2004 tdci 2.0, it would make a loud rattle noise from the gearbox.. when you put the foot on the clutch and press it all the way in the noise would go.

When we stripped the gearbox out we found that there was no oil in the gearbox at all, we fitted a new solid dmf, clutch and throw bearing and its still making the same noise from the gearbox any suggestions???

if the gearbox had no oil in it, it is likely there has been a lot of wear in there resulting in play and hence a rattle. if it rattles when stationary and the play goes when you put your foot on the clutch then the play is likely to be on the gearbox input shaft (the splined bit that slides into the clutch plate).   when the gearbox was off the engine, did you check if there was play there?

where had the oil gone? was it leaking where the driveshafts go in?