Just learned that the Aussie mokes that have longer radius arms had bearings in each end of the pivot instead of a bushing. Kits available for this. Look to be the same size as regular radius arm parts.
It's not all Oz Mokes. The longer rear arms were needed only when they switched from the 10" wheels to the 13" ones early on in the Oz production run. And they also had to add that kickup at the rear on the body to accommodate the bigger wheels. I didn't know about the bearring. Interesting.
I don't know why you couldn't bore the std size holes out to match the roller bearing on each end.....but there must have been a reason they didn't come this way from the factory on all the other cars - and a reason they did on the Mokes?
My guess is they made the original trailing arms "good enough" and when the Aussies made the longer ones they took a fresh look and found a simple improvement.
I mean consider that many Mini parts pretty much remained unchanged from 1959 until the end of production in 2000. The engineers might have had an appetite to improve things but they typically did not have the budget to make any changes/improvements. The only reason there was an A+ version of the A-series engine is because Austin-Rover were shamed into doing so when they had to put the Mini drivetrain into the "brand new" Metro in 1980 rather than develop a new powerplant. The A+ was done mostly to fend off criticism in the market of using an ancient engine (already nearly 30 years old by 1980) on a new car model.