307 Indicator Stalk?

Hi,

I've got a 307, with the fault that lots seem to have that when you indicate right and then turn, it automatically indicates left. it has done this for the last three years, however, it has failed it's latest MOT becuase of it. I managed to get a new unit and took it to the garage, but the mechanic says he does not know if it is compatible or not as peugeot's have different sytem's. I would need to know the chasis number of the car it came from to see if it is compatible with mine. I contacted the company I got it from and they are reluctant to give me the info due to car cloning, but said it came from the same make and year and if it is identical (witch it is) it should work fine. Has anyone got any ideas. My mate next door is an aircraft mechanic and reckons he could do it.