Looking For Wiring Diagram for 1992 LN1 (709 Series)

[Treggie]

Hi all, I badly need a wiring diagram for a 1992 Mercedes-Benz LN1 Motorhome/Camper (709 Series). I am in Australia and this unit is extremely rare over here, but may be common in the UK? I have recently purchased it and find that someone has made lots of changes to the original wiring. I'm hoping to reverse those changes. While it sounds like Mercedes might supply the info, apparently the cost would be huge (just not viable for a 33 year old unit). Any help would be greatly appreciated. Regards, Bob