Thanks - Mervyn's were helpful in that they explained that the early 76 4/4's were fitted with Lucas switches and these are now obsolete and they have exhausted the MMC stock - He gave me a series of Lucas p/no's for 4/4 switches but could not suggest other vehicles.
That's useful information.
Just did a little search on the HOE Morgan site and it looks as if they maybe have a few in stock. Good luck.
HOE spare 
