I think the serial number plate says it all. Serial Number 8757. My E27N crawler is about serial number 2400 and it is one of the last E27N crawlers as it is a late 1951 model although I have heard that the E27Ns were assembled in Australia for a while longer.
I don't know if there was any sudden increase in production with the E1A Major, so depending on how old the skid unit in the auction is, it may be one of the last made.
It is certainly not a common machine. That one looks like it would need some serious attention, but at the current price I would not think twice. I paid a lot more for mine, it was minus engine too, and I ended up buying a truck to get it home on top of that. You have to love crawlers though. They are not the most practical machines for general shows and certainly won't do road runs
Regards, Frank.
Real tractors don't need tin work to be beautiful.