My limited experience with the nylon unis is this....
I used them on the Moke many years ago for about 6 months. They were great, as they didn't wear like the rubber ones and seemed to give a more direct feel to acceleration (though this may have been wishful tghinking on my part).
BUT......
Then I broke a driveshaft while up in the bush and had to change it. I had a spare drive shaft, but not a spare uni. When I unbolted the uni, the centre yolk fell out, which itself was not a problem. However, inside the nylon cup are a number of fine roller bearing pins, and a number of these tumbled out into the dust.
The next 2 HOURS! was spent searching in the dirt for the rollers (I still didn't find them all) then cleaning them and reassembling everything. Although there were two rollers short when reassembled, it lasted for me to get home.
The next week I binned the nylone unis and went back to Rubber, until the next gearbox rebuild, when I had inboard CVs (plunge joints) fitted.
Although while driving in the bush over the years I managed to destroy one Hardy Spicer steel uni and numeerous rubber unis, I have never (touch wood) had a problem with plunge joints.
My conclusion therefore is the nylon unis may be good for road use, but I wouldn't use them for off-road (simply for the frustration factor if you drop those nasty little pins).
End of rant.
Watto.
But I agree that moulding them would be the best way.
