Special top link-pin and low-profile castellated nut. For some time the kit containing this pin and the bushes had a totally unsuitable Nyloc nut where the end of the bolt barely reached the nylon insert, let alone had three threads clear. I wouldn't use a Nyloc here anyway, it's holding your front wheel up! The Leacy repair kit:
However after using one of these kits I had occasion to undo it a few years later when working on a king-pin it came out cleanly but stripped its thread when re-tightening the nut! Fortunately I had a spare kit as one laid in for the other side wasn't needed.
Contrary to rumour, these bushes (described as 'barrel' type, and you can see why) have a steel sleeve in them. Obviously so as it's the sleeve that rusts to the pin meaning you have to hacksaw through the pin either side of the trunnion, then drill/chisel the remains out of the trunnion. There is talk of a poly 'top-hat' type which also have a sleeve, but the rear shackles use a top-hat type and neither rubber nor red (at least) poly have sleeves, which may be where the confusion comes from.
Hub supported. Either behind the bump/rebound bracket, or the anti rollbar drop-link if replacing the bracket at the same time (note the missing bump rubber!).
Nut and bolt squeezing the bushes into the trunnion, daub with Waxoyl (note the king-pin is inboard of the trunnion) ...
... but still needed a paint scraper used as a guide to wedge the bushes between the arms (old damper as photo taken on a previous king-pin job) ...
... which were also wedged apart, clamp-bolt slackened right off.