Help, I have a master cylinder fitted to my car which appears to have started leaking from of all places where the resevoir fits to the cylinder, I initially suspected the resevoir had split this is not the case it appears to be the seal between resevoir and cylinder.

I am strugling due to location of the cylinder to see the part number on the cylinder I think it is numbered 622 can anyone shed any light on the model it came from I believe it to be a for sierra. Do I have the complete number if not can anyone give the full number of the part to allow me to order a new seal kit

[Edited on 8/1/11 by austin man]