Viper or Nimbus starter generator

Hi,
Does anyone have or know of where we could source a starter generator (preferably two) for a 500 / 600 series Viper within the UK ? These are mounted upon the gearbox and not, like lower mark Vipers on the nose of the compressor face. The use is for ground running only, so the unit does not have to have paperwork and even non working but repairable units considered. Alternatively a Nimbus starter generator may be able to be adapted so again if anyone knows of one preferably two any help much appreciated – Any information, please send us a message.