[ChrisL]

Ron,
For what its worth, I was told that it was a 1950s Land Rover housing with a beefed up spring. Not sure of the accuracy of that info though. However, I can say that it is a very common size and bolt pattern (as found in many V8 Holdens here in Aus) except that the throw is different, so just make sure that you have that base covered if you go looking for an alternative.