Compare old and new parts.

Never mind, I'm a plonker
Put everything back together with old components, same problem. Scratched head a bit. Sat down to a cup of tea and felt something lumpy in my pocket - the correct castle nut.
So I don't know where I got the castle nut I was trying to fit originally from, but the correct one is much lower profile. Everything works as it should now, thanks. I just hope something else vital isn't missing its nut now!



Is the plate with the grease nipple attached that slides side to side attached by any means? Or just sandwiched between the rack and the covering plate, and moved side to side when the square nut things on the pins come into contact with it? Sorry for the vague terminology...

Sandwiched.
But see picture 3 viewtopic.php?f=4&t=4071&p=118129&hilit=Steering+rack#p118129

That's a good idea. I wondered about fitting nipples there too, but the old ones I took out had barely any wear on them, presumably because they're only subjected to a very limited range of movement, as opposed to to steering arms for example. Also I couldn't work out an easy way of drilling them through without having to deal with the existing hole for the split pin. I like your solution though, might steal it when I do the rack on dad's car.

Agreed the inner ball-pins, don't wear that much, but the guide ring does.
By greasing through the ball-pin, the surplus grease spills out and lubes the slide at the front.
Have also a small hole at the back so the guide ring gets grease as well.
Did mine in a lathe with a carbide drill(S)!, takes a lot of time, just drill 1mm at a go and back the drill out...
Also newer knuckles are not as hard.

the extra nut could be from the steering rack end or the steering arms on the wheel sides...

Could use a Nyloc nut
or
@AZL57 extra nut....but might need to make a half-nut as there is not a lot of spare thread.