This is a repeat subject. on this site.
anyway there are 3 different axle ass.
one has 23mm u joint with horible system of keepers.
I can get these but have to custom fit the new keepers.
I have also found a type of boot of a atv or whatever that works on them,, BRIGHT RED>
next is 27 mm.Bright red boot will work on it too . Allan has these u joints and Hugh has complete axles,, they are Very good and if your skilled can greed without taking boots off.
3ed is 30 mm type. over the shelf there is a U joint but has no greese fittings.
I have found one with fittings but I must machine them down a few mmm,s
so the cost per u joint is high
a great boot for these axles is aval. a Home depot in the central vac area. there about 3 ft long and a bit wider than the long hoses.
Very tight and must lube to slide over the steel spring collar.