Master gearbox

Hello all, I have a 2001 2.2 dci Master with a very noisy gearbox. I have seen a Gearbox from a 2.5 dci advertised at a reasonable price could anyone tell me if the boxes are the same please.. The numbers are the same except for the last three. Mine ends in 009 the one from the 2.5 ends in 011. Not sure what this number refers too. Any help would be gratefully received .
Thanks Neil