Does anyone know where I can get hold of a flat plate for an old Gitzo tripod. I think it's a 1970's aluminium model with a geared centre column, maybe a Studex? I want to replace the geared column with a flat plate to mount an Arca Swiss head. The diameter of the hole where the plate would fit is around 83-84mm. Second hand would be good if there's anywhere these tripods go to die. Preferabley in the UK.