Bevan McKee [ Mckees Garage ] at Elmore is a very good and very long term Allis C. _ Agco dealer although I don't think that McKees do many mods to the base machine. Dave Redden from Crystal Brook in S.A. is also one of the innovative dealers who do a number of Dan's and his own mods to the Gleaners before they go out of the shop. Agco's Australian home page is a little hard to figure out if you want to locate a dealer. Go to "AGCO Australia _ New Zealand" home page - Gleaner - Dealer locator. Cheers!
Take a good look to splines to see they are in good condition and not rounded from lack of grease at some time. This could cause a swelling affect on coupleing which could crack it and eventially fail. likely more posible on the steep grades. Also remember at one time a bulliton on final drive axle. I believe it suggests leaving lock plate for bolts holding bearing on off and then loctite hard bolts in. I forget what the year of that bulliton was but beware if axle is found loose. Must be something that can happen in the mountains or areas with 12 row heads.
Here is a link to info about Walla Walla in Washington state in the USA. Home of the Walla Walla Sweet onion and our friend Onion Farmer among other things....