Well I managed to get hold of a pair of reasonable condition Tanker and Stake Truck as well as a tatty Stake Truck that I have pulled apart.
It will be refurbished in a totally non standard cab and chassis colour and generally upgraded.
The "low friction" wheels were never a great idea although they kept a standard wheel look.
The thin wire axle was threaded through four coloured nylon bushes and the ends nipped over at 90 degrees.
The two middle bushes were trapped at the centre point between the chassis and the spring metal used to conduct power to the headlights.
The two outer bushes were pushed into the hollow wheel with a little glue. The outer axle was suspended in mid air to allow some crude suspension.
Whilst stripping the model down, I decided I would renew the grain of wheat bulbs (3mm diameter) and replace the wire and bush axles with brass tube.
You can see from pic in my previous post how poorly the original wheels fit on even a near mint / boxed example.
However, my brass axle idea, isn't a total success because I used tube the same diameter as the interference fit bushes.
The wheels rotate but need coaxing. A tiny bit of oil helps but a slightly smaller centre sleeve would stop the friction taking place under the conductor strip.
As it is, it will be on a display shelf so the wheels being a little tight isn't a problem for me.
Original wheel and axle diagram:

- axle method.png (6.52 KiB) Viewed 3487 times
Replacement axle diagram:

- repl axle method.png (6.09 KiB) Viewed 3487 times
Original axles ripped out ... one brass axle test fitted
(use pliers not fingers ... those axle ends are sharp):

- IMG_4220s.jpg (124.17 KiB) Viewed 3487 times
New brass tube axles fitted and body primed
(imperfections are battery leakage corrosion ... needs more work):

- IMG_4224s.jpg (212.89 KiB) Viewed 3487 times